Schedule 35 (where I get mine from) has some good information on microdosing on their site.

We're all different -- body size/type, tolerance, etc., so I would start low at 50-100mg/day and then follow a schedule of 4 days on/3 days off. Try it for a couple of weeks and be sure to reflect on how you're feeling daily. It's important to check in with yourself to see if you're noticing a difference in how you feel. You may need to slightly up the dose, or it may not be for you.