... Or how to buy yourself time without totally hobbling yourself.**
Giving stuff away isn't always bad. Giving tribute isn't an affront. Think of it as buying time. AI civs are more than happy to backstab you, there's no reason why you shouldn't give a little up to buy time or to bribe a war or for whatever reason even if it's a bad trade (not always but most people, much like with slavery, start from a point of "Oh you MUST be joking!"). Trades can be early warning systems, they can endear you to powerful civs until you've had the time to develop to conquer them, then can be used to bribe 2 powerful civs to weaken themselves against each other and acheive your strength level and you swoop in for the kill or just enjoy the parity.
Just be smart on who you're conducting ongoing trades with and who you might be alienating from them. Be smart on your religious choices and whose demands you submit to (until you can make then submit once and for all). If you're not sure and the diplomacy screen and your power level holds you on par with the leaders then just hold off until you decide who you want your allies to be.
Tributes and resource demands can be as much of an opportunity as anything else.
* F9 is your friend. Hit it, select Power from the drop down and know where you are. You don't need to do it every turn but you need to generally know where you are. If you're weak you're in little position (largely) to go antagonizing civs unless you're at a bottleneck and it's pre-naval units. EVen still you may want to consider at least triremes or fortify your "interior" coastal cities if you tick a lot of people off.
* Open Borders - Yes, this means that some civs are just scoping out your terrain and defenses. Of course they'd know that from the power graph how strong or weak you are anyway! So unless you're pulling a bottleneck/backfill move where you seal off a section of land to settle behind yourself at your leisure, it's not a horrible plan to get the +diplo bonuses from OB. At least until you know whose side you want to be on. Besides, this way you can scope out their terrain and possibly target resources as well.
* Religion - if you didn't found one and one spreads to your land, that doesn't mean you HAVE to change to it right away. Sometimes it's better to wait to be asked if you don't need other benefits from buildings or civics. Sometimes it's better to wait until the predominant one (or the one of the strong civs) spreads to you. You don't necessarily want to be siding with the weak, minority civ (again, F9) and it's you against the bullies. Unless that's what you want. The corrolary is that even if you founded one and you find yourself in the minority, it doesn't mean you shouldn't necessarily switch. Unless you're strong enough or like being at the bottom of the dogpile. Remember, Civ is fluid. You can always capture that other holy city later on or spread your religion further than that one and make it worthwhile for everyone else to switch.
* Tribute Demands - Often this will be the Civ who is strongest at the moment demanding things from you. But then again often it's not (or they're too far away though unfriendly lands to be a threat). Again F9. Also look at the relationships. If they're not on your border, but they're friends with someone who is it might be time to worry. If they're much weaker than you and have few friends, then it might be time to blow them off. Don't just reject tribute demands out of hand though unless you're the top dog or near it (or going to be near it when you rish buy). Remember that any trade buys you 10 turns of peace treaty that you can use to build yourself up or otherwise protect yourself. Ongoing trade (i.e. sheep for deer can serve as an early wrning sign for relations. But that doesn't mean you shouldn't watch for stacks of units at your borders...)
By the same token, don't give a really strong civ a key military tech or resources unless you're bribing them to go kill someone else. That's likely to come back and haunt you. One tactic is to research a non-AI tech path like Aesthetics or non-war techs and then trade that for your war techs. Since none researched it, you can trade it to many civs for different techs. Just make sure you're not sacrificing your defense to choose the orad less traveled.
If you DO decide to give a tech tribute then in the same turn look at what everyone else needs. You already gave the tech away, and unless you have no tech brokering turned on they're likely going to at least trade it to their friends next turn. You may as well get the tech/gold/whatever from it instead of them!
In other words, if you give a freebie (possibly intelligently, to the huge pitbull at your doorrstep) then see who else wants that tech and work the best deal for yourself from it. Often you can trade the same tech you just gave away for multiple techs from multiple civs. A smart civ trades from the bottom up though. Again, you don't want to make the strongest or second strongest civ stronger. That said, you might be able to bribe another civ to go to war against your nemesis. If you join in that's even better diplomacy with another strong civ.
Helping in war - Speaking of that, you can DoW (Declaration of War) on a civ but never actually go attack it and still get the Diplo benefit. It's a risk as it's possible that that civ may stay at war against you even after your pal sued for peace. But if you keep your strength up, they've got war weariness or it's just not worth coming after you you can declare war and after some time declare peace. Note that this works poorly against aggressive civs. They tend to have long memories and are somewhat irate. It may take some playing with this to get the feel but it can be worthwhile, even if you never attack the civ you declared on.
Warring - And speaking of war, not every war needs to be fought to the bitter end of your opponents civilization. Vassals are an option, but even if they won't capitulate (or you don't want them to), if you (or they) have alphabet you can often sue for peace for some tasty techs! No one's saying you can't eradicate them after the mandatory 10 turn peace treaty is done. This is a tactic that can be used to backfill techs if you got behind on in the war.
--- I'm sure there's more that I stumble upon, I just know that some of thise knee jerk stuff is what I struggle with (and when I overcome it it helps me... a LOT) if people find this useful I'll backfill this, if not well, I feel better
** Disclaimer, I truly AM a beginner-sort player, I win on Noble only sporadically. And while I'm trying to master the warmonger mentality, sometimes I just need some time to get there. These are things that my new butt found sort of works and stuff that I struggled with at the outset. I'd welcome advice from better players but (and it's entirely possible I missed it in the MANY good article here) I never really saw a lot that would counter my knee-jerk (and often bad) response to things in terms of diplomacy.
I also realize I'm tipping my hand to just how dumb I am, but surely I can't be the only one.
Giving stuff away isn't always bad. Giving tribute isn't an affront. Think of it as buying time. AI civs are more than happy to backstab you, there's no reason why you shouldn't give a little up to buy time or to bribe a war or for whatever reason even if it's a bad trade (not always but most people, much like with slavery, start from a point of "Oh you MUST be joking!"). Trades can be early warning systems, they can endear you to powerful civs until you've had the time to develop to conquer them, then can be used to bribe 2 powerful civs to weaken themselves against each other and acheive your strength level and you swoop in for the kill or just enjoy the parity.
Just be smart on who you're conducting ongoing trades with and who you might be alienating from them. Be smart on your religious choices and whose demands you submit to (until you can make then submit once and for all). If you're not sure and the diplomacy screen and your power level holds you on par with the leaders then just hold off until you decide who you want your allies to be.
Tributes and resource demands can be as much of an opportunity as anything else.
* F9 is your friend. Hit it, select Power from the drop down and know where you are. You don't need to do it every turn but you need to generally know where you are. If you're weak you're in little position (largely) to go antagonizing civs unless you're at a bottleneck and it's pre-naval units. EVen still you may want to consider at least triremes or fortify your "interior" coastal cities if you tick a lot of people off.
* Open Borders - Yes, this means that some civs are just scoping out your terrain and defenses. Of course they'd know that from the power graph how strong or weak you are anyway! So unless you're pulling a bottleneck/backfill move where you seal off a section of land to settle behind yourself at your leisure, it's not a horrible plan to get the +diplo bonuses from OB. At least until you know whose side you want to be on. Besides, this way you can scope out their terrain and possibly target resources as well.
* Religion - if you didn't found one and one spreads to your land, that doesn't mean you HAVE to change to it right away. Sometimes it's better to wait to be asked if you don't need other benefits from buildings or civics. Sometimes it's better to wait until the predominant one (or the one of the strong civs) spreads to you. You don't necessarily want to be siding with the weak, minority civ (again, F9) and it's you against the bullies. Unless that's what you want. The corrolary is that even if you founded one and you find yourself in the minority, it doesn't mean you shouldn't necessarily switch. Unless you're strong enough or like being at the bottom of the dogpile. Remember, Civ is fluid. You can always capture that other holy city later on or spread your religion further than that one and make it worthwhile for everyone else to switch.
* Tribute Demands - Often this will be the Civ who is strongest at the moment demanding things from you. But then again often it's not (or they're too far away though unfriendly lands to be a threat). Again F9. Also look at the relationships. If they're not on your border, but they're friends with someone who is it might be time to worry. If they're much weaker than you and have few friends, then it might be time to blow them off. Don't just reject tribute demands out of hand though unless you're the top dog or near it (or going to be near it when you rish buy). Remember that any trade buys you 10 turns of peace treaty that you can use to build yourself up or otherwise protect yourself. Ongoing trade (i.e. sheep for deer can serve as an early wrning sign for relations. But that doesn't mean you shouldn't watch for stacks of units at your borders...)
By the same token, don't give a really strong civ a key military tech or resources unless you're bribing them to go kill someone else. That's likely to come back and haunt you. One tactic is to research a non-AI tech path like Aesthetics or non-war techs and then trade that for your war techs. Since none researched it, you can trade it to many civs for different techs. Just make sure you're not sacrificing your defense to choose the orad less traveled.
If you DO decide to give a tech tribute then in the same turn look at what everyone else needs. You already gave the tech away, and unless you have no tech brokering turned on they're likely going to at least trade it to their friends next turn. You may as well get the tech/gold/whatever from it instead of them!
In other words, if you give a freebie (possibly intelligently, to the huge pitbull at your doorrstep) then see who else wants that tech and work the best deal for yourself from it. Often you can trade the same tech you just gave away for multiple techs from multiple civs. A smart civ trades from the bottom up though. Again, you don't want to make the strongest or second strongest civ stronger. That said, you might be able to bribe another civ to go to war against your nemesis. If you join in that's even better diplomacy with another strong civ.
Helping in war - Speaking of that, you can DoW (Declaration of War) on a civ but never actually go attack it and still get the Diplo benefit. It's a risk as it's possible that that civ may stay at war against you even after your pal sued for peace. But if you keep your strength up, they've got war weariness or it's just not worth coming after you you can declare war and after some time declare peace. Note that this works poorly against aggressive civs. They tend to have long memories and are somewhat irate. It may take some playing with this to get the feel but it can be worthwhile, even if you never attack the civ you declared on.
Warring - And speaking of war, not every war needs to be fought to the bitter end of your opponents civilization. Vassals are an option, but even if they won't capitulate (or you don't want them to), if you (or they) have alphabet you can often sue for peace for some tasty techs! No one's saying you can't eradicate them after the mandatory 10 turn peace treaty is done. This is a tactic that can be used to backfill techs if you got behind on in the war.
--- I'm sure there's more that I stumble upon, I just know that some of thise knee jerk stuff is what I struggle with (and when I overcome it it helps me... a LOT) if people find this useful I'll backfill this, if not well, I feel better

** Disclaimer, I truly AM a beginner-sort player, I win on Noble only sporadically. And while I'm trying to master the warmonger mentality, sometimes I just need some time to get there. These are things that my new butt found sort of works and stuff that I struggled with at the outset. I'd welcome advice from better players but (and it's entirely possible I missed it in the MANY good article here) I never really saw a lot that would counter my knee-jerk (and often bad) response to things in terms of diplomacy.
I also realize I'm tipping my hand to just how dumb I am, but surely I can't be the only one.