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, you probably condition and condition, only to end up with your hair plastered flat against your head. To avoid this, use a split-end treatment, a leave-in conditioner with light hold or a pomade just at the ends -- these can temporarily seal the splits.