When I put my bird on a little wooden perch or when she perches on my finger, she goes to my hand and starts nibbling/half-biting all over my hand. They don’t hurt too bad, but sometimes they sting a bit at first. She doesn’t seem to be jabbing at me aggressively; it seems as though she is exploring it/using me as a chew toy (she loves chewing). I was wondering why she does this, and how to get her to stop (I don’t want to make bad habits with her once she is older and may bite harder).
Your budgie is simply exploring your hand (normal), and budgies are similar to dogs in exploring by using their mouth. If this is going on when out of the cage you might create a perching area there with a variety of chew toys/sticks, hanging objects that she can chew on, with you close by. If you don't like the nibbling just slowly move her to perch in a new spot which is interesting to her.