Well, I used to do the same, i.e. Archer Armies, especially as I preferred to play more defensive civs like the English. I'm waiting to get another Xbox so I can get back online again, but in the meantime I've been watching videos posted by some of the better players to see how they do it.
http://forums.2k.com/showthread.php?246236-Civ-Rev-Video-Archive
At the moment I'm watching dukeblue1987's games. They are "head to head" (HTH) though, so only 1 other human player. Basically, he often seems to move his settler to get some local map knowledge and perhaps find a friendly village and/or barb hut, and then plants his capital.
Then he usually builds just 1 warrior (or possibly 2) to get some cash, then switches to research for horseback riding, then rushes horses and goes for the AI capitals and map knowledge to find his opponent. If necessary, he'll defend with warriors and sometimes bring his horse army back to defend a city, but the way he places his troops, he can usually get advanced warning of an enemy attack (although watch his German's vs French game if you get the chance, for a hilarious example where he *thought* he was going to get an easy win until the French launched an incredibly sneaky attack, and he didn't have a good enough defense.)
This is probably a bit more risky in a multiplayer "free-for-all" (FFA) game, where there's likely to be 3 human players. You can still try and grab their capitals but I would definitely consider archers in FFA games.
I guess it depends on knowing what's likely to be coming at you. It depends on what other civs are playing, and whether they're human or AI, and how many. If there's more than 1 human player (i.e. in a FFA game) I would aim to know where my enemy is, so at least I have a better chance of knowing when (and if) they're likely to come for me, and with what.
Arabs, they have Fundamentalism (with its +1 attack), so their horserush can be dangerous. Zulus, +1 warrior movement means they can be on your doorstep quickly. Aztecs like to horse rush because they get instant heal after an attack. Also Americans and Chinese, especially America if they get lots of gold early on.
It's tricky. Map knowledge is probably critical. I think that's another reason why so many players like to use horses. They get to explore the map faster.
One thing I've noticed about these top players is they don't usually bother actually forming archer ARMIES. After watching their videos, I now see why. Basically, let's say you have 3 single fortified archers in a city, and maybe a single horse. An non-Aztec veteran horseman army ["HA"] comes to your capital, with Infiltration (i.e. it's a Ninja horseman). Basically, I think that's 18 attack on your city!
If you have an archer army, chances are it could be destroyed by the HA, and they take your city. Two or three SINGLE archers means he probably has to use up several turns healing and attacking before he gets to take your city (unless he's Aztec and/or has the Blitz upgrade). During that time, you can hopefully bring another horse and rush a horse, form a horse army, and counter attack his army.
I admit I'm not an expert at this concept yet, as I used to do the archer army thing, but I've come to realize you have a much better chance of surviving an attack by using two or three single defensive units, and then follow up by counter-attacking his attacking unit.
Of course, it's a little more tricky if your opponent brings 2 or 3 horse armies! You can't easily defend against that, at least not early on. If you definitely know you're going to lose the city, one thing you *could* do is leave in a single warrior or archer, and bring attacking and defending units outside the city in a spot that is hopefully invisible to your opponent. When he captures the city with his HA, but before he has time to build defense, you re-capture the city so he loses an army, and move in some defense as well. Not easy to pull off, especially against 3 armies, but reducing him down to 1 or 2 gives you a much better chance of survival.
OK, I'm rambling, so let me try and write down the key points I can think of...
(1) Get good map knowledge, so you know where your enemies are; AIs so you know who to target for a possible early takeover, and human players so you know where the attack is likely to come from.
(2) Control any "choke points" on the map, with warriors or archers. Even if they get killed (not a big deal), you'll know about an impending invasion in advance.
(3) Use single warriors or archers for defense, to delay a takeover, and use attacking units such as horses, to counter-attack.
(4) The bigger your empire, the harder it is going to be to crush, so aim for more cities.
(5) Generally, don't use roads. (I'll admit, I always used to use them, until someone pointed out that they also allow your enemy to walk all over you as well! Sometimes roads are fine for strategic reasons.)
(6) Keep some units at strategic points on the coastline, so you can see galleys coming (giving you advanced notice of a potential "galley drop" of horse armies.)
(7) Press your enemies. If you're attacking in their territory, they're much less likely to have the time or resources to attack you in yours.
By the way, since I've been playing single player deity a lot while not being able to play multiplayer, after watching the multiplayer H2H ("head to head") videos, I remembered that the AIs in multiplayer are only at King level. That would explain why, with multiplayer games, it's actually much easier to take an AI capital.
As long as you leave contact as long as possible, don't get too close, and don't go to war with them, they're unlikely to have built archer armies until quite late in the BC's, but in my deity games they were getting there much sooner. So in multiplayer, killing the AIs is much easier. It's just the humans you have to worry about
