As far as sensitivity goes its important that you put windows sensitivity to 6/11, Counterstrike sensitivity to 3 and edit the dpi in your mouse configuration program to get the sensitivity you want. This is to get the optimal 1:1 sensitivity. Also you need to have mouse acceleration off in both windows and in-game.
Another option is to put raw-input on in counterstrike which ignores windows sensitivity and makes it take the sensitivity directly from your mouse instead, either way is fine.
For the dpi its really up to what you prefer, each company that produces gaming gear calculate dpi differently, so saying you have 600 dpi means nothing at all.
Most pro-gamers use a pivot point to move their mouse, either your elbow or your wrist to get the most accurate mouse movement. if you use your wrist as a pivot point you will need high sensitivity, if you use your elbow you will in most cases want very low sensitivity, in my opinion the best solution is to have the sensitivity that if you move your mouse to one side of your pivot and then over to the other side your character turns 360* if you use your elbow this will take the whole mousepad, if you use the wrist it will only take a small portion of it.