Religion is an addiction. Shed it. Seriously, you're way better off leaving the AI to found them
Excellent advice, at least for the three early ones. (Hindu,Budd,Jud) Confucianism and Taoism, you need the techs that grant them pretty quickly anyway, so it doesn't really matter if you found them. That being said, you don't *HAVE* to spam missionaries with them. You're better off going with what the rest of the cool civs are going with for diplomatic reasons.
i go on a limb here, suggesting another thing many new players forget
are you using enough siege? ... are you using it proberly?
You can never go wrong by building siege units. They are devastating when used properly. They can be used to soften up attacking stacks in your own territory to great effect. When used in enemy territory, bombard the opponent to 0% defense and then attack the city on the next turn, siege FIRST. Collateral damage destroys the enemy.
As a general rule, once you have 6-10 cities (less if you have a capable city or run out of room to expand), devote at least two of them to producing NOTHING but military units. The exceptions to this are to build any building that
A)Increases

(Forge, factory, etc.)
B)Increases military unit strengths ('racks, stables, drydock, Heroic Epic, etc.)
C) Increases

(this will become a problem).
Doing this *should* keep your power high enough to discourage your enemies.
Keep quite a few units in your border cities. AI's will see a small garrison as a weakness to be exploited. If you have Open Borders, scout their territory.
Don't underestimate diplomacy. Keeping good relations with some of the civs is pretty much a necessity for most of the game. Sharing religions, trading resources, trading techs, etc. are some of the best ways to keep your friends happy.
If you are afraid of an attack and not ready for it, and the civ in question demands a tech or resource from you, give it to them. By doing so, the game forces 10 turns of peace between you, giving you much-needed time to marshal your forces for the attack.
Another of my favorite methods to buy time is to bribe another AI into war with your enemy, if you feel an attack is imminent. (WHEOOHRN) Gift them a tech or two, some money, your map, whatever. Just get them to attack your enemy. Also great for softening up your target or diverting his main stacks away from your borders.
Hope some of the ramblings help out...