Scrimming is a big part of CS:S. This guide will help you on what you should do while you scrim.
Team Leader
Make sure you have the most experienced scrimmer leading the team in tactical strategies. You want to be well organized if you want to beat your opponents. Scrambling all over the place is going to get you killed.
Buying Weapons
The first round is the pistol round. All teammates should stick together on the first (and maybe the second round too). It is recommended that you don't buy anything but a defusal kit (Counter-Terrorist). Try to save your money for a while so you can have better guns later. If you happen to save enough money to buy an extra gun, give your broke teammates a better weapon if they ask. It's a good idea to post how much money you have so the richest player can buy the gun for your teammate. Some scrim servers have a mod that automatically shows your team money.
Never Rush By Yourself
Listen to the team leader and try to stick with at least one of your teammates, save the rushing for pubs. Only rush when you are with your teammate(s) and when everybody understands what the plan is. Sometimes it's smart to pause for a moment before rushing into an area. This will sometimes trick your opponents into thinking that you are headed somewhere else.
Think Realistically
Always act like you would in real life, like your life depended on every move you make. Slowly peak around corners. Make sure there aren't any enemies in the first spots you see before you completely peak around a corner. If you see an enemy, take cover and let them know exactly where the enemy is (and if possible, the weapon he has) and then try to take him out. If you spot more than one enemy, wait for back up or change your direction.
