The Free Application for Federal Student Aid is the first step in determining how to pay for college. It is not only used for federal aid, it is also used by colleges to determine your expected financial contribution (EFC) to the total cost of attending. This includes books and room and board. If you are accepted by a college, that college's financial aid office will work to put together a package of grants, loans, scholarships, etc, to fill the difference between your EFC and the total cost of attending that college. The likelihood of a given financial aid office meeting this cost difference decreases the longer you wait on applying for aid.
The springboard from which to start one's financial aid journey. Checklists, explanations of types of aid, eligibility requirements, instructions for applying, and info on loan management. If you visit only one site regarding financial aid, make sure it is this one.