I am mostly going to go over competitive strats. The first round in a competitive match is the pistol round. the one pistol you don't want to buy is the P250. It has armor piercing rounds but nobody has armor first round so you are wasting $300 first round. The default pistols work just fine for the pistol round. If you are CTs then you don't need to buy a pistol you can buys a diffuse kit first round to increase the chances of a diffuse or a hostage rescue. You want to play the pistol round safe because it will decide the outcome of the game.

The first half is super important for the game. If you lose all 15 rounds you'll probably lose the game. If you win 7 rounds and they win 8 you still have a chance to win. at the beginning of the second half there is another pistol round witch will decide the outcome of that half.

Eco rounds are almost the same as pistol rounds. They are to help you boost your economy to overpower the opposing team. The chances if winning an eco are slim but you can still win. If you win an eco you will probably be able to buy next round. if you lose the eco you probably will eco another round.

In a competitive match it is much harder to win when you play with randoms so get 4 other friends who play cs go and make a team. the chances of winning increase drastically with friends. with randoms its a 50 50 chance that you will win. If you use Curse, Skype, or Teamspek you can plan your strats easier than in the middle of a match.

The last round of both halves, the opposing team will buy AWPs, autos, Negevs, or another op gun. I recommend a gun you are comfortable with but don't peak anyone on the last round. At the EOG (End Of Game) every one says "GG" or "WP" or "You guys suck! Your ♥♥♥♥♥♥♥ noobs!" Don't be the last guy. Even if you lose you should be friendly and move on because in reality its just another game.