It sounds like TM helped you with logic games; I hope you scored well on the December LSAT. I was scared of logic games after I took a cold diagnostic. I worked on them very hard, though, and it payed off (21/23 October 2008). I grew quite fond of them, and I'm almost sad I won't get to do them any more.
I didn't take a Prep Course, but I did prepare well on my own for my October 2008 LSAT. I think developing a strategy for the LSAT is a very personal subject, and everyone will need to develop his/her own strategy to maximize his/her potential. The best one can do, in my opinion, is experiment with several different established sources, such as Prep Courses and printed publications, and incorporate favorable elements from those sources into one's personal strategy.
Becoming prepared for the LSAT will not happen overnight; for most people it is a process that develops over a period of 3-36 months. The beauty of it is that as one is experimenting with different techniques, one is learning how to take the test. By the time one has reviewed 2 or more preparation aids, one should be familiar with the different question types on the LSAT and have an idea of which ones seem harder than others. At that point one should be developing a personal strategy, working on improving difficult question types, and learning to manage time during each section.
I think a solid way to prepare for the LSAT is to take previously administered LSATs, one at a time, and then review the results. This review should consist of examining each question, even the ones answered correctly. Instead of relying on a book to explain why the wrong answers were wrong, though, I think it is healthier to examine the answer choices and make one's own determinations. I believe this builds mental strength, as well as confidence, because one learns to explain the answers better than any book can. This also encourages one to think like the producers of the LSAT, not the makers of the 3rd-party preparation materials. This, perhaps, is why some prep materials/courses can actually hurt you; they may help you in one area, but then they teach a method that clashes with your learning style in another area. The trick is to recognize it and discard what doesn't work for you.
When it comes down to it, I say screw the prep materials. Look over them, then put them aside. Just buy all the previously administered LSATs, take them one at a time, and figure out how they work (and how you work with them). That's what a lawyer would do!