Counter Strike: Source.

Tips on Playing Counter Strike: Source Like a Professional.

1. When you are getting attacked at short range (2 - 4 meters away), do not panic and spray all your rounds out. Back up and aim at the head, but make sure you stop and shoot rather then the bad accuracy you will get during the gun fight. If it is needed to spray, try to strafe side ways and you will have a greater chance of surviving.
2. When it is clear, cover and reload, this is a vital in most counter strike matches because 1 simple bullet, towards the head, or possibly any other part of the body can simply kill your enemy
3. When using the awp sniper rifle, always remember to bring a decent hand gun, I have always seen an awper trying to eliminate the enemy with a default pistol (Glock/Usp) considering that he has a better weapon
4. Always control your recoil, when you see a person and you end up spraying at him, do not continue spraying, instead take cover, and come back out. Most cal players always do this, but I tend to relocate so the enemy gets mixed up, then you can flank him from behind. If there is no place to take cover, simply take out your secondary and try firing 1 - 3 rounds, if there is no luck take out your primary and fire, you shouldn't have anymore recoil.
5. When you come up behind a person aim at head and fire, do not spray at him, I have seen a lot of people come up behind my teammate and kill him only to be shot and killed by me afterwards while he reloads. Conserve your bullets, since you never know when his teammate comes right around the corner.
6. Always take cover, pretend that every person has an awp, you will be on your toes and be aware of your surroundings, and this will help you eliminate the enemy before he can see you. When I walk down a long passage, I tend to take cover behind crates and peer out to snag an enemy before we make contact.
7. Always strafe, this will make it hard for the enemy to take shots, I always strafe, and when I hear him reloading, I go in for the kill

I hope I have shown you some basic points that every CAL or professional Counter Strike player knows, and you will go off and follow them.