Skin picking is also known as trichotillomania. It's more an anxiety symptom than a self-harm act.

I will "scan" my body for imperfections by passing my hand over my skin. If I find a blemish, pimple, scab, etc. I will pick it. The more anxiety I have, the worse the picking gets. Wounds start to grow in size. Stopping is difficult to do partially because I don't always realize I'm doing it. So I either have to keep clothes on all parts of my body (in winter), or I have to put bandaids on all the spots to make me realize what I'm doing.