Create your own
error log. Just keep a space for comments regarding a particular question.
I usually had question number, my answer choice, confidence and comment.
I would leave the confidence portion blank. If I was uncertain or guessed the answer correctly, I placed a ~ next to my answer choice. The comment would be the type of question it was -- divisibility, strengthen/weaken, find the conclusion, prime factors, rate, overlapping sets etc.etc. I also marked it off if it was one of those question types that I was weak at, but improved. Or if the question just piqued my interest.
After a while, you'll find your weaknesses. Attack these weaknesses!!!! Are you weak in reading comp? I was. I forced myself to do minimum 2 passages a day. I hated those remainder question, I did a search for all remainder questions here on gmatclub.
Study efficiently, not stubbornly.
And always, time yourself. No one cares that you can find the probability of being dealt pocket aces if it takes you 10 minutes to solve it.