Be sure to get good grades. A solid A average will be needed for most programs. Investigate graduate programs by the beginning of your senior year. Consider their emphasis and quality, as well as entry requirements. Most American programs are pretty similar, but there are some that have particular emphasis, often because of the interests of their particular faculty members.
Programs also vary in quality.
Some are well established with large experienced faculties and large professional networks which help in getting internships and jobs after graduation. Potential employers are likely to know the program, and a degree from there might carry more weight. There are many great programs from which to choose, even among those that aren't on anyone's top 10 list. Determining program quality is not always easy. Look also at the number of faculty and students.