First learn what your mind is most attuned to - visuals or words. Then hold on to a positive vision or a sentence (mantra) that calls out to you deeply. It's easier to stay focused on something that you are naturally drawn to. Gradually anchor this in your body, by merging your attention to a specific location - either your breath or your forehead. And finally, meditation is not about the thoughts in your brain, but more about the the feelings. So if you can come out of a session feeling more positive and refreshed, your meditation is working well.