Bring a variety of outfits – cap and gown if you’d like, I know you have a distinct look in mind, just remember that a cross section ie: something casual, as well as stylish/formal is optimal. This way, you will have photos that reflect who you are in your everyday life through to your ‘styled’ look.
Iron anything that needs it. Wrinkles show up in photos.
Bring props that reflect your high school years – band instrument, sports gear like a volleyball, baseball bat, paddle. I know you are into dance so maybe there is something from this you can bring. Favorite jacket, shoes/boots, sunglasses -LOVED the ones you wore yesterday!... Most of importantly (and I know you’ve got this), rep your style, whatever that may be. Your senior photo should be unique to your life and personality.
Think about how you want your facial hair to look or no facial hair...
Clean, clipped finger nails.