Individual (intermediate):

By this point you should know the maps, know how to throw nades and most importantly know how to kill people, so heres how to move from been a pub player to been a competitive player and how to really begin improving and becoming a known CSS player.

Equipment:

So we know you have a computer that can run CSS, some will have a good computer, some will have a really average computer, either way your playing CSS, now its time to buy gaming equipment. A good mouse with a good mouse pad is very important. Find out what mouse suits you and what mouse pad to go with it.

It can take a lot of research to find what mouse suits you, extensive tests by ESReality showed that the Razer Deathadder is rated the best gaming mouse. However they also tested many other mice, the MX500 and MX518 were a close second to the Razer Deathadder
Note: Not tested was the Mictosoft v3.0, a good mouse to look into and one I recommend.
There are lots of mouse pads which are good, my personal favourite is the SteelPad 5L, however everyone has their own preference, SteelSeries and Razer pads are the most common gaming mouse pads found, Icemats are also quite common.

Just as, if not more, important than a good mouse and mouse pad, is having a good set of headphones. Good headphones can virtually pinpoint where a running or shooting opposition is even when you can not see them. It will help having a decent soundcard, however if you use an on board soundcard do not get any headphones that require more than just the one port. My recommendation for under 100 dollars are the Zalman 5.1 Surround Sound, however you need a sound card which will cater for these headphones. Other headphones to look into are the Sennheisers which are the most common headphones for gaming however they can be quite expensive.
I would suggest getting a set of headphones which also come with a microphone so that you can start communicating with people via chat.

Here is a list of some of the things that you should look into buying:
Hardware

Mice: http://hardware.gotfrag.com/portal/story/30943/

Laser:
1. G5 (the newest version): http://hardware.gotfrag.com/portal/story/37478/
2. Copperhead: http://www.everythingusb.com/razer_copperhead.html
3. G3: http://hardware.gotfrag.com/portal/story/33776/

Optical:
1. Intelli v3: http://hardware.gotfrag.com/portal/story/34387/
2. MX518: http://hardware.gotfrag.com/portal/story/29947/
3. Diamondback: http://hardware.gotfrag.com/portal/story/35780/

Mousepads: http://hardware.gotfrag.com/portal/story/30830/

Cloth:
1. QcK (Heavy or Plus)
Heavy: http://hardware.gotfrag.com/portal/story/34839/
Plus: http://hardware.gotfrag.com/portal/story/31473/
2. Razer Mantis (speed variety)
3. Titan: http://www.bigbruin.com/2006/everglidetitan_1

Hard
1. Steelpad S&S: http://www.gamesurge.com/pc/hardware/reviews/steelpad_ss.shtml
2. Func 1030 Archetype
3. Icemat

Hybrid
1. Steelpad 5L/5C http://hardware.gotfrag.com/portal/story/30532/
2. Func f30.r
3. Razer ProSolution http://hardware.gotfrag.com/portal/story/30466/
Enjoy!

Headphones:
http://www.headphones.com.au/forums/viewtopic.php?t=7
1. Beyerdynamic DT234pro
2. Sennheiser HD555
3. AudioTechnica AD700

For all those who are looking specifically at 'Gaming only' headsets...

Gaming Headsets:
http://www.esau.com.au/article/hardware/34487
http://hardware.gotfrag.com/portal/story/30338/
1. Steelsound 5H
2. Icemat Siberia
3. Razer Hp-1's
4. Everglide S-500
5. Sennheiser PC150 range

Finding a clan:

Now you know how the game works, and you have decent gaming equipment, the next step is becoming a competitive player. As an unknown player, you will need to start off with a pretty average team, this is ok though, learn how to play with a team and how wars work (you can find a war guide here). To find a team for CSS you should download and IRC client and connect to “irc.gamesurge.net” in here if you are from Australia you can join the #gotgames channel, along with this you can join some of the major Australian team channels such as #f4f #team.imminent #team-encore #teamlivid and #virtue. If you are from America try joining #gotfrag or for the biggest clan in the USA #complexity. The channels above are the major channels where you can find some smaller teams looking for players.
Now it isn’t easy to find a clan, you can advertise that you want a team, but also if you see someone asking for a slut (ringer) take the offer and start practicing, if you make a good impression you might be able to join that team.

Learning how to war:

This is important, while you are warring, if you get killed, think about how you got killed, by who and why, once you understand how you died, alter your game so you don’t die the same way again, make sure that you watch the positions other players use and try them out yourself.
It is also good practice to go join pug wars, #csspug on gamesurge, because you will find some of the top players in here, watch them and how they play, try doing what they do and altering what they do to suit your capabilities.
There are 3 different players when it comes to warring, there are players who have outstanding aim and just pick off people one by one, there are players who roam around the map and pick off any players who are out of position, and there are players who play smart by hiding or waiting in the right spot. The quicker you work this out, the quicker you will start improving.