Can you solve the problem with ease, explain it to someone who can't solve it and write a similar problem with answer choices and explanations? Congratulations, you've mastered the problem! To master an OG problem
1) Solve the problem (this may take a couple of attempts)
2) Study the solution (if you have gmatfix OG Companion, use that solution as it's a lot more thorough)
3) If you've missed the quesion, go through it again with the explanations to guide you
4) Once you're able to solve it, record the problem in a questions log to be addressed later.
5) A week later, redo steps 1-3 above. Can you solve easily and efficiently? You're the master

Can you do it but with difficulty? get back to it in a week.