Which homemade acne treatments are considered the best?

Try them all: Painting your face with vinegar, sleeping with your body plastered with honey, and smearing with enough tea tree oil to make a man grow breasts are all options. I can't vouch for any of them, and if you want something that really works (and especially if you're caring for a young person who has acne) get with a scientific physician like you would if you had any other serious illness.