Simply redo the books before trying ANY practice exam.
1. Start with OG. do the tutorials-> practice questions ->
2. GMAT (official CD) -> tutorials
After completing ALL official materias you can expect a decent score 600+. But remember: just reading is not allways enough ! study rather than reading. It is really good you have already identified your weakness. Give extra efforts on the topics.
Make sure that you have already internalize ALL the the OG materials and content BEFORE approaching MGMAT / Varitas.
AT the same time: make sure to attend / study 5 question and discussion on each section (PS, DS, SC, CR & RC) every day in GMAT Club and Test Magic. (lunch hour study!)
Hope you all the best.
After 2 month revert to this Post.
dont intimited by the RC and CR while studying OG 13
. If required memorize the logic. (it will certainly boost your confidence.