Have fun.
Always remember the play in cosplay. Try your best to be a good cosplayer, but don’t take it too seriously. There won’t be cosplay police hiding behind bushes at your next con.
Get to know your character.
Cosplay is roleplaying, so be prepared. Practice your character’s accent if they have one, and study his or her background in case someone asks you questions.
Accessorize.
The more fine detail in your costume, the more impressive it will be to fans. How you accessorize will distinguish you from other cosplayers dressed as the same character.