If you are getting a burner, pay in cash at a store. Try for a store without a lot of cameras. Wear a disguise or face covering, or have someone Smurf it for you. Get a bag that blocks cell signals or get a model with a completely removable battery. Never use it at home or work. Put your own phone in a signal blocking bag prior to using the burner. Don't let your signal overlap. It will be complicated to completely cover your tracks.

Do not use fingerprint and cover the cameras. This includes IR sensors and stuff.