Some of my friends found the powerscore CR bible very helpful. Perhaps you might consider checking it out if you have the time. Personally, I didn't rely on it.

I initially used diagramming on paper, but after doing so many questions, diagrams just formed in my head (I think others have a similar exp as well with practice). That helped save some time during test day. However, whichever technique you go for, make sure you practice till you're comfortable with it and it becomes 2nd nature to you. Good luck!

thanks, this is one of my worst topics i m just not getting it maybe ill try the CR Bible

CR passages are usually one paragraph long so there is no need to diagram them. While diagramming and sketching are essential in RC, they are just waste of time in CR.