Cosplay

I suggest someone mainstream so that you can get a lot of ideas from other people on tips / tricks, and that if you want to buy the costume, it'll be easier to find.
Some suggestions, however I have no idea what you're interested in: vocaloids, mainstream shounen mangas (Naruto, Bleach, One Piece, My Hero Academia), or idol games/animes (Idolish7, Love Live, Ensemble Stars).
On the flip side, do someone who you look up to, if none of those categories fit you. Maybe your favorite seme/uke, some girl in a sailor uniform, a video game character, etc. I hope you can find someone who really speaks to you!