I would suggest searching Google, Cosplay.com, and DeviantArt for pictures of cosplayers, art, and fan art to try and mimic from those results.
Usually art from the show has their signature pose as well as different facial expressions they are known for. Find a few poses you like then practice in front of a body length mirror so you can see exactly what someone else sees when they take your picture. It does help discoverer where your wig might show hair or unflattering angles.
Message me for Photoshoot scheduling and information for any con I am attending.