After you have exhausted local and institutional options, national databases are worth a pass.
BigFuture by College Board (bigfuture.collegeboard.org) offers a free scholarship search alongside college planning tools.
Fastweb (fastweb.com) and Scholarships.com are the two largest searchable databases.
Going Merry and Bold.org are newer platforms with lower-competition awards and simpler applications, which makes them a better use of limited time than the large databases for many students.
Two practical notes. Set up a dedicated email address for scholarship searching, because these platforms send frequent messages. And never pay to apply for a scholarship or to access a scholarship search; legitimate awards do not charge application fees.
Set expectations honestly. National awards have applicant pools in the thousands. Local awards from Card 15 and Card 16 are a far better use of your first ten hours.
Sources: BigFuture, bigfuture.collegeboard.org; Fastweb, fastweb.com; Scholarships.com; Going Merry; Bold.org.