How come? Is this also true if you play Tradition or Progress?
I'm more likely to place guilds in my capital if I play tradition, but in general I usually end up building all wonders/national wonders and such in my capital, meaning it usually falls behind on buildings without having an extra 6 cultural specialist to work, not to mention 3 extra buildings to build.
That being said if you go Tradition into Aesthetics, you should probably build your guilds in the capital, but I tend to play more Progress than tradition.
I know that the early game techs depend on what kind of resources you have around you. That said, a lot of resources only get revealed after they are researched.
Is beelining a good idea to the more advanced tech right away? For instance, if you research the tech that reveals horses, do you beeline straight so you can use horseman right away?
I find getting range +1 archers kind of almost make/break the game usually. That makes it feel like researching trapping is actually quite a high priority.
Any general plans for early game?
Completely missed your post
In general, if you're in the forest/tundra, go for trapping, as there is usually deer around, on non-forest non jungle, your safest bet is Animal husbandry, it could be a total miss as flatlands could also mean stone or bison, this is assuming that you're not on the coast, if you are on the coast you could just as well have Fish. If you have 2 or 3 wheat tiles, you probably don't have any other bonus resources, and you can instead go for like the wheel or something like that. In heavy jungle you're most likely to have bananas. In general, going for sailing or Calendar first is a poor idea, they are too heavy of a tech-investment unless you know for sure that you have those resources near you, which you only do if you have researched all other bonus-resource techs and found nothing. You usually want Animal Husbandry and possibly Bronzeworking by the time you finish your first settler, so you're not in the dark with regards to strategic resources when making your settling choice.
I usually don't build that many archers, I find warriors decent enough at clearing out barbs, if I have trapping available I might pick up an archer or two, but I don't go out of my way to get them, but then I usually don't reach +1 range with them, 4 promotions takes heavy experience-farm to get. I do play on standard speed however, and I've heard that promotions are way more common on marathon/epic.
About bee-lining for horsemen, it is a fairly heavy investment, both in tech and in hammers, horsemen are expensive and you also need to prioritize a worker and improve the horse-tile, they are however really strong so it might be worth it. I'm personally more likely to pick up chariots instead of horsemen, mainly because they are cheaper.
As for a general plan, my goal in the early-game is usually expanding and making sure I don't die. As long as you have cities, infrastructure and you're not dead you can usually recover from anything. That being said sometimes I mix it up and try to go for an early wonder, if the situation calls for it. The early-game is really all about playing it enough to get a feeling for what you can get away with without dying.