The first lesson in sniping is to find out which gun you will be using. There are four sniper rifles in CS: The Scout, The AWP, The SG-550, and the G3/SG-1 Precision Sniper Rifle. The first task is to determine which sniper rifle suits you best for the map. The scout is 2750$, light, bolt-action, and will take about 2 shots to kill ana enemy. The AWP is 4750$, heavy, bolt action, and will take an enemy down with 1 shot most of the time. The SG-550 is 4200$, medium-weight, semi-automatic, and will take a few shots to kill an enemy. The G3/SG-1 is 5000$, heavy, semi-automatic, and is more powerful than the SG-550.
Basically, you have to pick a rifle that will suit your needs. If you are going to be very mobile, you might want to go with the scout. Its very light, so you can move quickly with it. The AWP is pure power and is good for people with decent aim. Even a glancing blow can kill someone. The semiautomatic sniper rifles are mainly for support, and for people with less aiming ability. They really aren't that useful, unless you're screwing around. You're better off with one of the bolt action sniper rifles, or a regular rifle.Secondary Weapon - Once you've picked out your rifle, check to see what your secondary weapon is. A good pistol is key to any true sniper. If you're on the terrorist side, you might want to buy a different secondary weapon. Personally, I think the glock is a piece of shit, and I don't buy a sniper rifle unless I have enough money for a different pistol. The pistol can be used for close range, or to finish off an opponent that has already been hit by a rifle.
Hiding spots, backup, buddies - When sniping, make sure you get a good position with good cover. Also, your teammates should know where you are, and you should know where they are. One good strategy is to have a sniper buddy; someone with an assault rifle or submachine gun. If things get close, its good to have a friend to back you up and vice versa.
Personal Defense - A lot of people use flashbangs, grenades, smoke grenades. Make sure you can easily escape grenades, and be careful not to look at flashbangs. If you turn the other way, you wont be blinded as much. Smoke grenades can also hide the enemy. be careful to watch your back when there is smoke covering on entrance.
For more advanced techniques with a sniper rifle, click on the advanced strategy section, or right HERE