TLDR Anapana: Sit comfortably and monitor the sensation of the breath exiting the nose and return to it as your thoughts wander. Don't get mad when you wander, it's part of the process. Just return and try to maintain equanimity, to not react. If you get frustrated at first, you can increase your exhale slighlty to make it more noticeable.
That's about all there is to it. After you do this for a while your thoughts become less and less frequent and... you only have important, creative thoughts :) It turns out conscious thought is just a refection of a deeper process and most of it is garbage: worries, self doubt, fears.
I have just inspired myself to take up daily Anapana by writing this...