re: criminology. No, I haven't taken it but that's because my uni doesn't offer it. From what I know of criminology it sounds interesting and highly related to law. Happily, we live in the internet age so you can probably find free criminology lectures on iTunes U, or on youtube, or a ted talk, or something. You can watch one and see if you like it.
re: philosophy. I've done enough philosophy subjects for a major. Some philosophy subjects will not have exams at all and have you do only essays in your own time. Others will have one exam and an essay or two during the semester. Generally, an essay in philosophy will involve investigating the work of a philosopher and showing that you understand what they said and that you can come to a valid interpretation of their work which is based on evidence; or it will give you a philosophical question and you will need to provide your opinion on it. Philosophy essays tend to be quite difficult at first, but once you get the hang of them they are fairly easy. Unlike a lot of disciplines, philosophers seem to like it when you take a humble approach to essays, you just answer the question logically (not necessarily saying anything new) and come up with a rebuttal for a common argument against your position. They don't like it when people overstate their case or generalise too much.
Majors advantageous to the LSAT: Arts subjects generally give you a good background because of the reading and analytical thinking involved. Philosophy gives you a more formal method for logical thinking (particularly if you take a Logic course). Maths grads are apparently the best performers on the LSAT, probably because they would all have a rigorous background in logical thinking. Other than that, having a bit of a versatile background could be of use. On the LSAT, questions come from all different scenarios, including politics, science, literature, the law, and they don't take out the jargon! There can be some quite academic analyses in there, as well as more journalistic pieces. At the end of the day though, I don't think that necessarily means that you should do subjects just because they might help you on the LSAT, GPA is also important, so you want to do subjects you like and will do well in.
Other than taking a course in logic, the only thing I would definitely recommend is to read lots and widely, even books and articles that might be a bit of a challenge for you. Reading newspaper articles everyday is also a good habit to get into generally. To prepare well for the LSAT, it may be advantageous for you to read articles from different news sources so as to increase your mental flexibility. Try to follow all sorts of news, even if it doesn't interest you as much. Again, luckily we live in the internet age, so reading a variety of news everyday is both free and easy.