Hi there,

I don't know which materials you have used so far, but in my opinion trying to understand the concepts solely from the OG if you are not proficient in Math, won't help much.

In my opinion, depending on your current level of proficiency, try to get some of the well-known prep books such as Manhattan GMAT 8 Strategy Guides, Princeton Review etc. After you go through these books you should be familiar with basic concepts and ready to attack OG problems much easily.

However, sometimes even if you go through these books you can still feel weak at some areas. In this case, try to search for on-line resources as there are plenty web sites which cover almost all Math sections in-depth.