There are plenty of threads dedicated to answering this question. See:
http://talk.collegeconfidential.com/sat-subject-tests-preparation/1595279-the-math-level-2-exam-a-comprehensive-guide-for-an-800.html
http://talk.collegeconfidential.com/sat-subject-tests-preparation/1616013-general-guide-to-getting-800-on-sat-ii-math-2c-p1.html
http://talk.collegeconfidential.com/sat-subject-tests-preparation/1864637-tips-for-getting-800-on-sat-ii-math-2-subject-test-by-a-perfect-scorer.html
http://talk.collegeconfidential.com/sat-subject-tests-preparation/1365443-guide-to-an-800-math-level-2-long-edition.html