I totally agree with "heygirl"
I'll illustrate a simple approach.
You'll need:
1. OG, 12th Edition
2. Manhattan SC Guide
Step I: Choose a set of questions from the OG
1. In the OG, SC section, question number 1 to 46 are easy, 47 to 92 are medium and 93 to 140 are hard. So select 3 easy questions, 2 medium questions and 1 hard question.
2. Try and answer them on your own without timing yourself. When you answer each question, write down why you think the option you chose is right and why the other options are wrong. Then compare what you wrote with the explanation given in the OG. Since each answer choice is wrong on multiple accounts, you'll always notice that you overlooked certain errors in each answer choice. Maintain a list of these errors you overlooked. If you have any doubts regarding the rule stated, consult
Manhattan GMAT immediately and read the relevant chapter.
3. Repeat the procedure till you finish all the questions in the OG.