no short-cut for CR, mate! Be prepared for long-term fighting.
Read sdcar2010's post:SDCAR2010【逻辑入门】汇总 http://forum.chasedream.com/GMAT_CR/thread-571267-1-1.html It will give you a holistic understanding of CR. Personally, I find it is very helpful.
After that, work on the OG, and analyze all wrong and right answers one by one. You can use GWD to practice, it is very similar to the real GMAT test questions.