Don't for get the guest of honor

Do treat this as the formal and special occasion that it is. Ask the guest of honor for their input because after all, the bat / bar mitzvah party is all about them and should follow their tastes and interests. Create a theme and even a menu that is in line with what they would like. Do try to keep the occasion as formal as possible, but try to keep it personalized and it will create an amazing and memorable occasion.