Before I give you any suggestions, this is a
monster thread that talks about EVERYTHING you'll possible need to know.
36 and 19 are not your average scores and might indicate a fundamental weakness in your preparation and knowledge. But it's not impossible to bring your score up.
1. Get the
MGMAT or Veritas Prep Math Fundamentals book. I've heard good things about both the books and I am sure it'll help bring you up-to-date on the basic concepts.
2. Then, if you can, enroll in a Knewton class or buy either the
MGMAT Bundle or the Veritas books. These are comprehensive resources that will definitely aid you in your preparation. Choose between them - they're both good.
3. Get the Powerscore CR Bible. Definitely get
MGMAT SC.
From here on, devise a strategy that would basically involve a familiarization phase and a practice phase. First gain proper understanding of concepts. Don't do practice questions on a brute-force method during this period. Take notes. Once you're done, start doing questions. Definitely get the OG 12, OG Quant Review and OG Verbal Review if you haven't already. Start working on practice problems and keep an
error log. Initially do the problems untimed, but once you're achieving a good hit rate on all question types, switch to timed practice. Use the
error log to identify weaknesses in your study.
Then finally take practice exams and see where you stand. If you're consistently scoring >700 in your practice tests (esp. GMAT Prep), then you're in good shape. If not, go back and re-do your problem areas.
Hope this helps, and good luck!