Some Artists have placement preferences, and some won't tattoo certain areas. If the Artist is okay with the placement, the rest is largely up to you.
Your Artist can offer their professional opinion about where to place the design.
Some placements are drawn with a certain shape or flow to fit your body correctly, so deciding on a desired placement with your Artist is usually helpful. Artists can ask you to specify a placement (and size) when you Book a Wanna Do design or submit a custom Booking Request.
Sometimes designs may need to be re-drawn if the placement changes, which could take time. Be sure to give your Artist a timely heads up if you're considering changes to your design or placement.
Still not sure your placement will work? Message your Artist to talk it through.