One surefire way to increase your chances of getting into law school is to maintain a high undergraduate GPA. Many schools offer pre-law courses and provide advising to pre-law students. Take advantage of these options, as many law schools reward applicants who have taken particular courses in their undergraduate years. Keep in mind that law schools look more favorably on majors that are perceived to be more substantive or relevant; a double major with the same GPA as a single major has a leg up.
Obviously, a high score on the LSAT is crucial for getting admitted to law school. Hire a tutor or take test preparation courses (Kaplan and Princeton Review are good resources for both). You can also purchase an LSAT preparation book or obtain LSAT materials for free on the LSAT website.
If it seems like a particularly difficult year to get admitted, or there are more applicants to law school than usual, a good option is to do some volunteer work or gain employment in a law-related field. This will look good on your resume and allow you to apply at a more fortuitous time.
Some law school applicants choose to hire a personal admissions consultant. These professionals have years of experience getting customers admitted to law school and may be able to provide you with helpful guidance.