You are very wise to start early. There are lots of things that you can do to improve your chances for getting into a top law school if you start now. When you say top law school, I am assuming that you mean top 3-5 schools in the country, and will base my comments on that assumption.
The LSAT is the biggest factor in getting into a great law school. You will need to score in the 170's (99th percentile) to have a good chance at getting into these types of schools. Use REAL actual previously administered LSAT tests, and plan on devoting 300+ hours to studying for the test. Remember it is worth considerably more than your GPA when it comes to chances for admission. If you can find a course that will allow you to study for a year or two that is a huge plus.
GPA is the other quantifiable factor that affects admissions. For the schools in question a 3.7 would be the minimum for a good chance of admission.
Choose a major that you will love. One common mistake that people make is to major in political science, english, or philosophy, because they think that law schools will be impressed by those majors. Actually, you have a greater chance for admission at the top schools if you DON'T major in one of these, because it allows you to bring a different viewpoint to the law class than the herds of applicants from those majors. I was recently meeting with the former dean of Yale law school with a high school friend of mine. When this issue came up the dean stated that majoring in music would give this young man a better chance for admission than political science if all other things were equal.
That said there are some classes that you should take to improve the reasoning skills that will help you to do well on the LSAT and in law school. Take whatever formal logic/quantitative reasoning classes are available at your university. Also, taking statistics, and upper division writing classes in philosophy will be very helpful.
When considering these particular schools you should also be looking to publish as much as possible. Submit articles/papers to student journals, and try to work with professors that may help you get published.
Establishing connections with professors early on will be invaluable for cultivating letters of recommendation later on. Visit them in office hours, and try to get teaching/research assistant postitions.
Volunteer work will only be valuable if you can show a consistent pattern of service. So be sure that you are always involved in some way in these types of activities. Helping out in the juvenile justice program is usually possible in most states, and will look fabulous on resumes.
Your personal statement is also going to be a big factor in admissions, but that is far less quantifiable than the other elements. There are lots of things that you should avoid doing, most significantly waiting until a few weeks before the deadline to write it, but that is far enough in the future that I won't spend time here talking about it.
Well, that may be more than you wanted to know but it will at least get you started, if you want more advice down the road I am always happy to give it.
My hubbies ex was in a similar situation. Her son got out of the house while the grandma was watching him. The police were called and the mom (not grandma) was issued a letter saying if they were called out again for this child on neglect that he would automatically be taken. They never got involved in the situation they just sent a letter to her stating that if they were notified.
They are just bullies. You should try some sort of legal aid or put your case out there for pro bono work??????