Dude here's my 0.02c for improving you verbal.
1. Learn the basics of GMAT SCs from Manhattan GMAT SC
guide. Then go through OG (even if you have completed once) and for each SC categorize the errors. MGMAT SC
book also points the ERROR in each of the choices in OG. That's too important to miss.
2. For CR and RC practice - do lot of practice. Initially don't worry about time. Learnhow to solve the questions and with further practice, it is always possible to improve on speed. Refer to Princeton GMAT book for introduction about CRs and question types. For practice you can use the CR1000 and RC1000 from the verabl section of this site.
3. Most importantly focus on OG! Read OG explanations. They show you how to arrive at the correct answer. I used only OG11
While my score in Verbal is not stellar (V36/80%), I would have been in worse shape had I not studied MGMAT SC
book and OG!
Read Rhyme's post and learn as much as possible from his techniques http://www.gmatclub.com/phpbb/viewtopic.php?t=30030
And even if your Quant is really good, don't just kill urself with Verbal prep. Everyday parctice a few DS and PS too.
"To dream anything that you want to dream, that is the beauty of the human mind. To do anything that you want to do, that is the strength of the human will. To trust yourself, to test your limits, that is the courage to succeed."
- Bernard Edmonds