Hey there!
I studied using the Kaplan MCAT, it's pretty comprehensive in regard to each of the subjects covered on the OAT. Since I've been out a year I reviewed EVERYTHING. I think the test is very hit and miss so I would touch on everything if you have the time for it, better to be prepared in all areas than skip something that you could have known if you only looked over it ten minutes or so. I did also purchase the KAPLAN OAT guide for the practice tests and math questions as the MCAT does not have this section. I studied for about 3 months, but I was also working a 10-7 job so it was somewhat sporadic at times. My scores are pretty consistent, which is better than having a 390 in one sections and a 280 in another I suppose. Here is my advice for each section:
Bio: Bio was easy for me since I have B.S. in bio, so I basically went through the Kaplan MCAT review and was set. It wasn't so much the material of questions I encountered as much as I had difficulty with the phrasing of the questions on the test. I'm a slow reader so I sometimes got hung up on phrasing, but overall I didn't get too many random questions. Have a general knowledge of each of the areas and you should be good. Had a lot of genetics questions, x-linkage, genetic abnormalities, etc. Good thing that was my fav class as undergrad!
Chem: Chem for some reason was hard for me, and I thought it was going to go better than organic chem. Definitely know colligative properties, types of rxns (redox, etc). There weren't too many computational questions and the ones that were there were simple numbers and I can't recall using too many equations. Know limiting reagent, rate constants, acid base reactions/ph, etc. Half life problems showed up for me in both this section and physics!
Organic: organic wasn't too bad. My overall study goal for this was to group reagents together by TYPE of reaction. For example, if you see KMNO4, O3, etc, you know it's going to be oxidation so you would look for a product with a carbonele or OH or what have you. Like wise H2/Pd, LAH, etc are going to be reduction so look for a loss of double bonds or loss of oxygens. If you have aromatic/cyclic compounds, know if the reagent is going to attack the substituents or if it is going ot undergo ortho para meta addition. I think taht's the most useful way rather than trying to straight memorize exactly what product from each reagent is going to look like. A lot of my questions were conceptual about orbitals and meso compounds and enantiomers, so definitely know your concepts- I think that helped more than anything because I didn't feel very confident on identifying products for rxns.
Physics- very few computational, again, know your concepts. I expected an elevator problem for sure but never got one! I think if you know your equations and know the concepts behind them you would be fine. There is absolutely no time in this section to derive equations should you need to, so definitely write them down during the break and refer to them should you need to calculate something. I had almost NO work problems that I remember, couldn't believe it.
QR: This section was the most stressful for me and the only way to prepare for me was doing pratice problems. Also, know your 30,60,90 and 45 triangles, they WILL show up multiple times (at least they did for me). I had a few trig identities that I wasn't prepared for (csc, cot, etc) and I had really only prepared for sin, cos, tan, and a few identities. If you don't know it, MOVE ON. In some problems it's just helpful and faster to plug and chug from each answer to see which answer fits best rather than thinking it through to figure it out. I did really well in my practice tests for these but being computerized and timed were not condusive to my test taking skills.
RC: Skim skim skim, then move on to questions. If you have to write paragraph number and one word to represent topic so you know where to go back to. None of my passages were hard to understand, again it was the time working against you. It's really helpful to practice before this section just so you know your own strengths.
Overall I would really pay attention to each area of the test, I'm really glad I did some practice in reading and math because I knew what to expect. Once you start studying you will get a feel for what you know and what you don't know. I see a lot of people on here taking a practice test without studying at all just to see how they do, which I don't think is a good idea and is a waste of time in some ways. I think study as hard as you can first bfore you take ANY practice tests, not only will it make you feel more confident but you will also know what areas you are stronger and weaker in. Hard work definitely pays off, so even if you think you know it still at least take some time to review. 🙂 Hope that helped, I know it's somewhat vague! It does seem like a lot of material to study but having the MCAT guide helped focus everything for me, and once you start reviewing it won't be so intimidating. 🙂