Think. Start there.
Whether you're going for the "clear your mind" sort of meditation, or the "open your mind and see what happens" sort, start by thinking. If you think better when you're still and/or rigid, or if you think better in motion (personally, I prefer pacing desu), do that. If you don't know when you do your best thinking, experiment. Try thinking while you're cleaning your room and washing your penis; you are cleaning your room and washing your penis aren't you anon? Memes aside, that's important regardless. When your room is clean and your penis is washed, sit down and think. Be mindful of your thoughts, and figure out when, why, and toward what they occur.