Hi!
Welcome to wine :-)
The best way to start doing something is to pick something you want to work that doesn't work they way you like it. Since you mentioned Counter-Strike Source you have done that already :-) . In the course of that you will stuble uppon more things that need work for sure.
A warning though, Wine is a pretty complex piece of software, and the APIs it implements are very complex. Getting started can be very tough, so don't give up too early ;-) Of course we will try you to help you as good as possible.
I am a bit puzzled that you say Cs source doesn't work properly. It should run next to perfect in dxlevel 80/81, I have made a lot of fixes for Crossover for this game. In dxlevel 90 there are some problems left though, namely the missing support for sRGB textures.