I use the headband simply as a "reminder" that surgery was done and only have adults wear it when they sleep to protect the ear from being accidently folded. It should NOT be tight as it could interfere with blood flow to some of the skin and cause scarring. Your surgeon is the best person to answer your question
How large and how tight should a headband be after otoplasty?
No dressings, compression garments or headbands should ever be tightly applied over recently operated areas. The headband essentially serves the purpose of protecting the ear from accidental bumps, and to remind the wearer to be careful and considerate of the recently operated area. Select a headband that prettty much covers the ear. Wear 2 headbands side by side if one alone is not wide enough to cover the ear. Look for headbands at sporting goods stores.
How to wear headband after otoplasty?
I would say that it is best to ask the question of how to wear your headband after otoplasty with your particular surgeon. Your surgeon is most familiar with your procedure and would be able to give you the best advice. In general, usually a headband after otoplasty should not feel tight and should primarily be used on the upper part of the ear. Your particular procedure may determine any variation to this aftercare, so please check with your surgeon to be sure.