I'm not sure about you guys but I think it would be a great Idea if Pros or people who think there Pros at the game just post tips for the people who are starting out or just having trouble. Feel free to post what you think might help them out.

My Tips:

• Patience is Gold: Even though it seems like the game is fast paced try to take it slow on really tight maps ( Office for example ). If you lose your cool to soon then your done for.
• Think of a plan: Odds are if you play the map long you'll understand where most people will come out, so have a plan ready for that, Either it will be camping or something else just think of the way other people play.
  

It takes FOREVER to get to being a good player. Don't expect yourself to be awesome in just three months or something. It take some years to get some good headshots.

The best tip I can give is use your ears, I can't recount how many kills I get because of my speakers, if you're attuned, you can hear enemies from meters away.

Use grenades to your advantage. flash a room you suspect your enemy may be in before you enter. and like Nobility says, use your ears. just listen for your enemy's foot steps and you will know when they are coming!

Try playing on a deathmatch server if you can't handle getting owned every round and just waiting there.

Actually use spectating mode to your advantage, and watch how others play.
Many people have different styles but it helps to gain knowledge on how they think and react in certain situations.

Also - Bunny Hop and Aim for the head. =D
But not until you get the jist of playing normally.. tactically.

• Fortune favors the brave: Players on CS:S usually expect a camping strategy, especially in leagues. It becomes a campfest for Counter-Terrorists on de_ maps. Try rushing once in a while, it completely throws off the opposing team.
• Get a mic headset: Seriously. It makes the game easier by allowing you to hear footsteps more clearly and communicating enemy locations and strategies becomes a breeze. Also, talking with people just makes the game more enjoyable.
• But don't talk on mic if you haven't gone through puberty: Just don't.
• Watch out in AWP hotspots: mid in de_dust2, long a in de_dust2, long hallways on cs_office
• Strafe, Stop, Shoot: Moving targets are always harder to shoot. But you have to stop for that millisecond to get off an accurate shot. If you can get this technique down, I can guarantee you a better kd ratio.