I took the MCAT last spring, and started studying right around this time last year. I followed the Kaplan books, but stopped using their practice tests because I didn't think they modeled the test well (they were way too difficult). I used the end of the chapter Kaplan problems though, and bought question packs from the AAMC. I also bought two full-length practice exams from the AAMC. This was a re-take for me, and the first time I took the test in the new format. I scored incredibly well, and I highly recommend the AAMC's practice problems and tests.
Quick add - I was incredibly scared to start actually practicing problems at the beginning, because I knew I'd suck. But practice is the ONLY way you'll beat this test.