Are you using the
MGMAT Guides? If so, maybe you can check out
Manhattan GMAT forums. A lot of the tutors from that prep company discuss certain strategies used to attack specific problems. They reference specific pages in the guides alongside the problems.
If your question is relating specifically to the
MGMAT Quant Guides and you are having trouble translating the strategies from there to the problems in the OG 12, then check out the
MGMAT Official Companion. The book is the newest addition to the Quant series and explains every problem in the QUANT portion of the OG 12 using the strategies from across the GMAT Quant series. I believe the book is available in an online version as well.
I have not used the book myself but I am going to look at it this week. I am sure it will be helpful since many people find some of the OG explanations weak. Using both explanations (OG 12 and
MGMAT) will help find multiple approaches to a problem--something that will be very useful on test day.
Hope this helped. I can update mid-week with how helpful I am finding the OG Companion to be.