Counter Strike is one of the hardest multiplayer games to get the hang of that I've ever played. It took me a week before I got the hang of the weapons for each side, and learned not to rush in guns blazing all the time.
Learning the maps can only come from experience really, but make full use of the free-look mode whenever you get killed to look for hiding places, vents, sniping points etc.

When you start off on a map, you pretty much have to use the pistol for round 1 - maybe buy a HE grenade, but in general save your money.
I'd advise doing the same in the 2nd and 3rd rounds, and keeping back so you can run in and pick up the weapon from a downed enemy/teammate.

That way when you want to get a kickass weapon, you can afford it.

Pistols are rarely useful for buying unless you're short on cash - for the terrorists the only viable option is the Dual pistols, and for Counter Terrorist you should really just not bother.

Sub machine guns can be very useful if you're on a map where you're not going to run into more than 2 people at once...aim for the chest and hold down fire and the recoil should send the sights up into the head after a second.

Machine gun - this can be fun, as it has 100-round clips, but it is not always that useful for killing people. It takes a lot of practice to kill and not be killed with this, but having said that, there is always a lucky kill to be got from a stray bullet. -Useful for backing up teammates in a firefight-

Rifles:

the ak47 for the terrorist is a great weapon, aim at their feet, tap fire twice in succession and you often get head shots...rush them, aim at the chest and hold it down and you're gonna kill them if you don't get shot yourself.

The Magnum is a one-shot, one-kill device which is great but has a REALLY slow reload time. Great for sniping, not good for up-close and personal fighting.

Shotguns - the
Auto-shotgun is the weapon of choice for rushing around a corner and firing into an unsuspecting enemy. It takes 8 shells and can be fired whilst reloading which is great. Not good at long range.

Ammo - don't forget to buy spare

Equipment:

HE grenades - come in handy on levels like Dust
where you see an opportunity - use it.

Flashbang - great for blinding opposition, but remember it'll blind you and your teammates to. So either save it for when you're in trouble or tell your teammates you're using it at the start.

Kevlar, Kevlar + Helmet - can be useful but won't help against a headshot really.


any questions, post them as comments and check back

Ken