The more praise you have in your file for your academic abilities, the better off you'll be. Law schools know that. Although they appear to be the place where you have the least amount of control, students actually have much more control over the quality of the recommendations than they think they do. You give the recommenders the information from which to write the recommendations. You start choosing recommenders in your first year of college by taking your coursework seriously, doing quality work, getting good grades, speaking up in class, and building relationships with professors outside the classroom.
Professors have office hours.
Professors give talks on and near campus. Professors write books and articles. Even if law school feels years away, speak to the professor at the end of the course and ask him or her if it's okay for you to come back at application time and get a letter. Yes, professors are your best recommenders. The best students may go so far as to pick and choose recommenders according to the skills required in the professors' classes or according to the professors' disciplines.