Honestly and thoroughly examine your characteristics as a student and ask yourself some key questions: Are your grades stellar? Are you a top ranked athlete in your state? Do you belong to a minority population? Were you raised speaking a language other than English? Are you the child of a member of the U.S. military? Any number of these factors can determine eligibility to scholarships. Consider what makes you distinct from other students and there is a good chance you can find a scholarship program looking for students with that attribute.
Increasingly, students look to the web to find scholarship applications. Sites such as Fast Web and FinAid are private companies that compile thousands of scholarships. The U.S. Department of Education also lists scholarships on its website. Also consider using general search engines to search for specific scholarship types for which you may qualify. Lastly, many specialty or minority group organizations have scholarships detailed on their website.
Your own high school's career counselor is an invaluable resources that too many students ignore. While the web certainly has more scholarships than your counselor can possible remember, she is highly experienced at searching for them and might be able to recommend scholarship types you have not considered. Your counselor can also be a resource for completing the scholarship application in as strategically beneficial a manner possible.
If you have friends or relatives in college, ask them about their own success with scholarships. They might be aware of scholarships, grants, or other programs that you would be unlikely to otherwise discover. Speak with older friends and relatives who have strengths and other attributes similar to yours.