@ALG: Thanks for all the tips. Most of this I've already learned during the past 2 weeks. I studied a number of openings so far. I've played Ruy Lopez a few times, and the Sicilian defense comes up a lot too. I get stuck shortly after the opening though and don't really know what I'm trying to do except move my pieces out and hope to setup some attacks.
I also went and learned how to checkmate with the most common combos in the endgame, like a King and Rook against a King. I haven't gotten to use these techniques except against the computer though. I'm getting so dominated in the mid-game that I'm usually checkmated well before anyone can promote a pawn. Usually around the 10th move or so, I already find myself in a situation where I'm trapped into either losing material or giving the opponent a major positional advantage. There's obviously something I'm just not seeing there. By the time I can see the traps coming, it's usually too late for me to avoid them. I don't know if I'm just blundering with bad moves or if I'm just blind to being intentionally setup by my opponent.
My weakest part right now seems to be what I do after the first 4-5 opening moves. I haven't been able to figure out how to develop attacks and keep my pieces defended at the same time. Whenever I try to be aggressive and setup what seem like good attacks, I end up down material. Whenever I try to play more defensively, I end up getting boxed in and picked up.
While I appreciate the strategy of chess, my weakness seems to be short-term tactics. I can't execute my strategic goals even when I want to. I tell my soldiers what to do, and they just get themselves killed.
The friend I played with a couple nights ago told me I should study tactics, so I think that's what I'll look into next. I need to find a way to improve my mid-game play. That's where I'm really getting killed right now. By the time I've reached the endgame, the situation is already hopeless, and my more careful moves can only delay checkmate at best.
I've already learned a few basic tactics like forking and pinning, mainly because they're always being used against me, and I've been able to execute them a few times, but I know I still have a lot of patterns left to learn.
I suppose the biggest question mark for me right now is: What exactly should I be trying to do after the first 4-5 opening moves? When I look at the board at this point, I don't really know what I should be looking for. Sometimes I'll try to set a long-term goal like setting up for an attack f7, but I've never been able to execute these plans effectively. Meanwhile when I look at what my opponents are doing, I'm just amazed at how perfectly they seem to execute plans.