I recommend you go to the US Supreme Court website and pick a few cases to listen to or read the transcripts, and if they have published the briefs to definitively read them. There isn’t really any undergraduate class that is better preparation versus starting early to read case law and legal writing.
The best courses that you can take are those that give you a good command of the English language and excellent communication skills. Therefore you should take advantage in English course, grammar, writing, speech, speed reading, reading comprehension skills communication skills in general. If you are interested in being a trial lawyer I also recommend that you take a drama class. Trial lawyers need to be good storytellers, therefore acting skills will be beneficial. There is no undergraduate major that will prepare you for the type of learning and studying that you will do in law school. The skills I have listed above are those that you will need to succeed in law school.
Jeanette recommends the following next steps: