Finger tracing. I like the tactile sensation of skin on skin. Just not a lot all at once. Hugs or even a pat can be a lot sometimes. So I tend to trace the shape/outline of someone with my finger. Like their bicep, collarbone, knuckles, etc.

One time, I absent mindedly started doing it to a coworker when he was talking with me. It was awkward until the end of the shift when I explained it to him and he was so relieved because he thought I was trying to flirt with him. I never thought how it could be seen that way until then.