I'm a senior in high school (I graduate in two weeks) and I want to go into law. I know that I canít take the LSAT until 3 years from now, but I'm wondering if I should start studying for it.
First, congratulations, both as to graduation and as to being very much ahead of the curve in knowing what you want.
The short answer is: You don't need to worry about the LSAT or practice area yet. It's very good to keep these in mind, but the primary focus should be in the following: Doing very well in college, in a subject you genuinely care about; being careful about money; and being reasonably careful about everything else.
Doing well in college will give you options, including law school, and will also help you in preparation for the LSAT. When the time comes, you should spend as much time studying for the LSAT as you spend in a full semester of study. Here's where your foresight will pay off: if you're planning your college years carefully, you can take a higher load during other semesters (and perhaps a summer or two), leaving a light load for the semester you'll be taking the LSAT. Then, give the LSAT all you've got. Don't worry about "not being good at math" (although you should try to get comfortable in math--it really does count).
Law school is a marathon. Nearly everyone treats it like a sprint--and it's natural to do so--but it's a marathon. Take the following four years to prepare yourself for law school, and you will do very well indeed.