The best way to stop picking your nose and eating its contents is to change your behavior by covering your fingers. This tactic forces you to be more mindful of your bad habit each time you attempt to pick your nose.
According to PsychologyToday.com, picking your nose and eating its contents could stem from a compulsive disorder. Small steps like wrapping your finger with tape is an effective and less extreme tactic to help you correct your habit. Each time you attempt to pick your nose, you'll notice the uncomfortable feeling of tape inside of it. Over time, this will prevent you from repeating the same habit due to the uncomfortable feeling.