Hostage maps (cs_ maps)
T's generally camp or guard, you pick the term... Camping/Guarding involves a player staying at his spawn point, or other secure location, waiting for the opposition to come to him. Simply put, in Facility when the Ts wait and snipe the CTs coming through one of the doors. Since Ts are supposed to protect the hostages, this is considered honorable. CTs have no such responsibility so CTs are "camping" rather than "guarding." It is considered reprehensible for CTs to do such. Likewise, CTs are "supposed" to "rush" or charge the Ts. If Ts were to do this, àla Siege, it perceived the same as CTs camping. "Rushing" is usually an effective tactic for a winning team, whether it be T or CT however. It gives the opponent little time to purchase weapons and Kevlar, and can lead to a quick win. For this reason, losing teams may also try this tactic.

Basically rushing for terrorists is a whole lot more worse then camping as a CT, in fact camping as a CT is just fine, although level design usually forces the CTs be the one to storm the fort. Cs_assault can result in absolute deadlock if CTs camp, as they can't get in, and Ts can't get out. On all other cs_ maps though, there is no excuse for CTs to be camping, as it will only result in the CTs losing the match due to their failure with regards to rescuing the hostages.

Defusion/C4 (de_) maps
T's are generally on the offensive! Rush towards the bomb spot, plant the bombs and then go to defense. Usually the CTs guard the bomb spot, waiting for Ts to come along. Once the bomb is planted CTs must rush in and defuse it!

Assasination (as_) maps
CTs on this level must rush, as its the easiest way to win. If the VIP doesn't get to the escape point, you lose, so practice sprinting across the level, and finding the quickest routes. Ts, on the other hand, have the luxury of being able to camp at the escape points, and if these are well enough covered, the CTs will have very little chance of success. Find good places to hide that have good views of the escape points, and stick with them.

Once you have decided your basic tactic, you must then execute it. You should defend yourself (outlined later) and evade the opponent (also outlined later). Sneak up behind your target and give a few rounds to the head from your MP5 or a slug to the chest from a G3 (example weapons :D) from afar. There are many ways.

You should master favorite your weapon. This will require practice. However, do not neglect other weapons, you may pick up an AK-47 and need to use it. Learn the ins and outs of all the weapons. You may have a favorite, if so use it if you can. Develop your own special tactics with weapons.

Strafing (moving horizontally) while firing from a gun will increase the spread of your fire. If the enemy is in motion, this can get you aligned with him for at least a few rounds to hit. It also prevents you from being shot at as well.

Ducking is very useful, most players will be running around and will probably miss a whole lot, while you have excellent accuracy!

The most important thing is to shoot first, but only shoot if you can kill. Do not take a shot if you cannot take down your opponent. Doing so could result in death. You don't want to die, do you? Thought not. If someone is running in your direction, don't start taking erratic shots at them. Wait for a clear target, as there is no point in giving up your position so you can cause him 10% damage. If you can see him and he can't see you, go for a head shot. Take your time, and this particularly applies to panicky snipers, who as soon as they have someone in their sights, they fire, regardless of whether or not they hit them in the head or the foot. Stay calm, and go for the head.  Be cautious yet strong. Practice. Practice. Practice. Play and you will get better, get a buddy to practice with you. Whatever you do, do something.

New players shouldn't try and rush ahead, but instead stick to the middle of the group and try to give cover fire. There's no point in being mowed down first, especially if you're new to CS and don't know the level design. Get to know the level, and never run around a blind corner. Go slowly, check behind blind spots such as boxes as you run past, as many a time entire squads of players have been mowed down by a camper with a Para machine gun who was hiding behind a box that they didn't bother to look behind. As an important anti-camper technique, always buy grenades of some sort. They are ideal for flushing out someone who is camping in an "unbeatable" position (e.g. on a ledge above a door). Using either HE grenades or Flashbangs can give you a few valuable seconds in which to rush in and finish him off.

Armor is an important part of defending. If you're sitting in the same place, chances are you'll be taking a lot of fire, so armor will come in very handy for stopping the occasional bullet that might hit you in the head.

The ideal weapons for defense are sniper rifles for covering large areas, or shotguns for covering small ones. Nothing can get past a terrorist with a xm1014 shotgun covering the vent on assault. The high rate of fire, and large blast radius means you get your man before he has a chance to fire. See what works for you, and try different combinations of weapons. A sniper rifle on cs_siege works wonders for both teams, as CTs have a nice sniping spot up on the cliff, while Ts can sit down in the tunnel and shoot the CTs long before they get anywhere near the base.

An important part of defending is knowing when to give ground and pull back. If the area you're in starts to fill up with enemies, it's time to get the hell out of there. Fall back to an area that is easier to defend (preferably a small corridor with a rifle or a large area with multiple snipers). Try and memorize all the places you can fall back to, such as a  narrow door which can be easily defended, with only one way in or out, so there will be no surprise attacks. New players should always try and stick to the back of base defenses, as the best chances of stopping an enemy is a strong front line of defense, with cover fire coming from the weaker players.

Just remember, defending is really attacking only with the primary goal being to keep yourself alive.