Honestly I just started by winging it. I played a lot of sport as a kid and just started by doing some of the stretches I learnt growing up. Then you can kind of figure out which stretches you like most and what order you like doing them in. The key thing for me was really just inserting it into my existing routine. So if you already have a workout routine you can just add it to that. If you don't then you could try doing it first thing in the morning when you get out of bed, or last thing at night before you go to bed.