Shooting on the floor is a real rush, but it's something that's reserved for photographers with official access. Fortunately, getting the go-ahead at many colleges isn't as tough as you might think. Your quest for a credential usually starts at the team’s sports information officer. Most schools -- especially the samller ones -- are eager to drive up attendance so they may appreciate the exposure, even if it's just on your blog. SIDs will usually offer spots to as many shooters as they have space for without making the floor totally packed. You'll also likely have better luck starting with lower-profile games. Establishing a good relationship can help you earn a spot during big games later on.
If you can't procure a pass, there's always the option of buying a ticket and shoot from the stands.