Perhaps this will be redundant, but I thought I would give my two-cents.
In the majority of cases laws schools only look at your GPA and your LSAT. So choose an undergraduate that you would enjoy and succeed in. I personally found after first year I did very well in philosophy. And as a bonus I learned philosophy students on average score the highest on the LSAT.
In concern to the LSAT, I would suggest you wait until the year before you are applying and write it in June. Why June? Well you have time off from school to study for it. As well, it is the only LSAT that is written in the afternoon instead of the morning. Perhaps you are a morning person, but I certainly am not. Even if you do poorly on it you can also then rewrite it in October or December.
Try to pick out approxiametly 3-4 professors that you could ask for a reference. I know you generally only need two reference letters, but in my final year I discovered that my two favourite professors where moving. I still used one, but the other moved to Texas which was too far for mailing back and forth information. Of your 3-4 professors try to ensure you have at least two classes with them during your undergraduate. Perferably one of which is in the year before you apply. As well, try to save great essays from the class to include in your reference request package. Of course, it is uncertain if the law schools will ever read their reference letter, but it is good to have outstanding ones.
At the end of day, law schools may not look at anything beyond numbers. But if you get put into a "maybe pile" at a holistic school it can be very helpful to have something that makes you distinct as a candidate. For instance, a friend of mine was a McGill Poli-Sci student who had a 75% average and a 80th percentile on the LSAT. By June he was rejected from every school he had applied to except Queens. U of O informed him that their reason for rejecting him was that his reference letters were not outstanding. Nevertheless, in late July Queens called him and told him that they would take him if he decided right away. When he asked them why he had gotten in, they said it was because he was on the McGill student council for a year.
It is hard to say if you will ever need anything beyond good numbers. It is hard to say what law school you will end up wanting to go to. Or what kind of law you will want to practice. So the best advice I can give you, is take a shot-gun approach. Make sure all your bases are covered. Do well in school, on your LSAT, become involved, know your professors and have fun doing it.