The next few years of graduate school are usually focused on finding a topic and an advisor for their dissertation, along with additional coursework and teaching assistantship or research assistantship. Applications for graduate school are typically due in December or January. Applicants should start writing away for the application forms in September of their senior year. One should expect to apply to 4 or 5 schools. On this page you should explain why you want to go to graduate school, and include some idea about what sort of research you would like to conduct.
Good grades are important, but they can be measured in different ways.
Some universities may recompute your GPA without freshmen classes, or your GPA for upper division courses, or only for course in your major. Most graduate programs are looking for a GRE score of at least 1000 on the quantitative and verbal parts. Your application to graduate school will also involve some letters of recommendation, usually three of four. Most of these letters will probably be from professors in the department where you got your undergraduate degree.