I have a different way of meditating. Instead of clearing my mind and trying to not think of anything (which is as good as telling me not to think about a pink elephant), I take whatever thoughts come into my mind and learn to recognise it, set it aside and move on. Basically not focus on it in an irrelevant way, I do that before I sleep, just to let it wash over me and then file it into a corner. It also helps if you can focus on your breath and a point slightly above your navel.
But I never manage to do it for long. After a while my mind starts to wander again. Usually in a very disturbing and slightly worrying direction.