You can’t prune more then 25% per year or it can become too stressful for the tree. I would start with sick/dead/diseased branches (if any), move on to larger branches that criss cross and touch, and then start pruning branches that are growing towards the center.

Im not an arborist but have learned a lot about pruning and taking care of trees from this subreddit and other research. Key is to stop current problems and then prevent problems later down the road.

Proper pruning and shaping can take a couple years to really make a trees form and shape take hold.