Well, as far as guns go, I would think it just depends on your style of play, mood, the level you're playing, and how much money you have.
If you're in the waiting mood, and you have lots of money go with the AWP Sniper rifle. Make sure you've found a few good sniping spots on the level before you do this though. Personally, I suck with this weapon, but I have played people that are incredible with it.
If you're in the up close, personal and pissed off mood, a level that has close quarter combat, and have a good amount of money, I usually like to go with the auto shotgun. I'm almost always guaranteed at least one kill when I use this weapon. Weakness is that you have to be pretty close and I've also gotten complaints from people saying that I was using the "noobcannon":disgust:
Soapbox: Why do people complain about this? Why would this game have this weapon if it is cheap or whatever? Equivalent to the lightning gun in Quake 3
If you aren't sure if you are going to get into a close encounter or far, the most versatile weapons, and you have enough money, then get the M4A1 if you're CT and the AK47 if your Terrorist. These guns are the best to use for any kind of distance, but the further your enemy is, make sure you do burst instead of automatic(tap the fire instead of holding it down). If you have a little more money than that, use the bullpup or the Krieg. These guns have a zoom option also.
If you have absolutely no money, but have enough for a big gun, get the smg. Not as good as the M4A1 or AK47, but still effective.
When I have no money at all, sometimes I'll just buy a Nighthawk handgun(best) and just go for the head shots and pick up a big weapon.
If anyone disagrees with this or has more info, I'm interested in what you have to say. Always looking for more pointers.
Hezaplaya, care to share how to do that? I don't like to cheat, but I would really like to cheat against a cheater. That sh1t really pisses me off.