Half of the cure for split ends is prevention:
Don't brush your hair too much, and be sure to use brushes and combs with smooth, wide-set teeth; avoid nylon bristles. And no matter what, don't brush wet hair! If you have knots, use a wide-toothed comb or your fingers to gently detangle from the ends up, one section at a time.
Elastic bands -- even the covered ones -- and barrettes can cause breakage. If you put your hair in a ponytail, use a scrunchie; when wearing barrettes, take care not to catch hair in the metal clip.
Of course, a trim will rid you of split ends instantly. In the meantime, a split-end treatment, a leave-in conditioner with light hold or a pomade applied to the ends can temporarily seal the splits.