Getting Better....

[OMGBEARS]

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1) Invest in a professional gaming headset

5.1 true surround sound or 7.1 virtual surround sound is invaluable. It stepped my game up further than anything else I put money towards. Professional gaming headsets (such as the Steel Series 5h v2) are optimized for games like CSS and emphasize the frequencies that games use for sounds like footsteps, reloads, picking up the bomb, beginning a disarm, etc, etc. With my headset I can literally hear players exactly where they are on the map if they aren't being very careful before I can ever see them. I can also differentiate footsteps to tell how many there are, and how far apart they are.

2) Invest in a professional gaming mouse

Gaming mice (such as the Razer Deathadder or Naga) are developed with games in mind. That being said, they have a much more powerful tracking laser for improved accuracy as well as missing a few benefits of stock mouses or office mice. Those benefits include a really lame tool that non-gaming mice include which is the mouse can detect when you are trying to draw a line and cancel out small movements up or down. Anything under 5 degrees won't change the path of said mouse. With gaming mice the curser goes EXACTLY where you want it to with no filtering out small movements. A steady hand can be incredibly accurate. The day I got my death adder I tripled and quadrupled my score as a sniper in TF2. The stronger DPI laser and higher ultrapolling means lower response times and faster acceleration which translates into your crosshairs moving exactly when you want them to as well as when you left click you fire exactly when you need to without adding more than the absolute minimum to your response times.

3) Mouse Sensitivity

I started playing with very high sensitivity (around 9.5) and noticed that once I switched to a higher quality mouse (death adder ftw) that I got better results the lower my sensitivity was. Now I play with 2.5 for CSS and TF2 and it really works out wonderful. Low sensitivity and a big mouse pad (a gaming mouse pad - ~1foot/~1foot pad) will do great things for your accuracy. You have to move your hand around more, but you can also make extremely small adjustments if you need to. It takes some getting used to, but changing my mouse sensitivity alone helped me out big time.

4) Invest in a high-def monitor

Different monitors are better for different things. Some lower-quality monitors are opimized for viewing pictures. Some are optimized for watching video. You want ones with high refresh rates as well as high color and contrast quality in order to insure that when the enemy is there you can 1) see him and 2) react in time. HD gaming monitors are the best for this. You need to be able to SEE the enemy to kill him.

5) Learn about different weapons

Each weapon has a semi-unique recoil and are better for different circumstances. As ZERO and Loka mentioned, with the AK47 the recoil is up and to the left. The p228 is more accurate than the desert eagle when jumping or in the air. Weapons also lose their accuracies after a different number of shots. M228 is good for about 1 bullet before becoming extremely inaccurate at long ranges. The AK is good in bursts of 2 before losing accuracy, M1 can be used in bursts of 3, that sort of thing. It takes time to learn the popular weapons intricacies.

6) Watch demos of professional players

You can find demos of professional players on sites like ESEA which can teach you a lot of invaluable things. When to buy and when to save, what to buy when, hiding places, sniping spots, team-play stratagies, methods of throwing the different kinds of grenades, when to reload, tricks in terms of faking out the enemy (throwing a smoke grenade in place of a flash, or beginning a disarm then looking around for the enemy to pop out, for instance), these sorts of things can be learned from watching demos of professionals that have taken years, in some cases, to learn can be observed and absorbed by you in a few months time of dedication.

7) Play a lot

The more you play with proper techniques the better you become and more instinctive they become. The goal is to know when to switch to your pistol if you need to reload, when to flash, how to attack a position, how to defend a position, when to retreat, how to treat different weapons in different situations, which weapons are good for indoors fighting versus fighting at long range, etc, etc.

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You can expect to invest around $500 into professional gaming equipment beyond your computer tower. ~350 on a good monitor, 80-100 for a good headset and 80 on a good mouse.