Inner or outer forearm
The inner forearm is flat and paler, so thin lines stay crisp and the design faces you when you look at it. The outer forearm is on show more often and takes more sun, which fades fine work sooner.
Long designs suit the forearm best: they can run from wrist to elbow and follow the arm. Round designs sit well on the outer forearm, just below the elbow.
Fitting it in the editor
Forearm designs open in Wrap, which curves the edges away the way the arm does. Raise Wrap strength on a slim arm, and photograph the arm in the pose you usually hold it in: a design that looks straight with the palm up can twist with the palm down.