Here is SS4’s piece on wrapping in general, with a little on girth. This is one of our best threads on wrapping for girth.
I wrap at the base using a strip of Theraband about 2” wide. I don’t spiral. The trick is getting the correct tightness, which requires some trial and error. It gets easier with practice.
To initially build the pressure I get a partial erection and repeatedly pull the wrap back toward the base as I kegel. This forces blood in front of the wrap. Once the engorgement starts it continues and is self-sustaining to some degree if your wrap is right. Usually my dick deflates over time. Every so often I do the partial erection/wrap pull/kegel maneuver to rebuild the pressure.