Elektra likes to go out on her own, even though it often gets her captured as a result, but that works well for the villain in the end. She's very flexible, so she can be tied in a variety of poses, but something that emphasizes her hips is the best way to go about it for her. It's also a good idea to tie her arms spread away from her body to keep her from accessing any hidden weapons she may have on her to cut loose. Stick with a gag that shows off her lips as they are as nicely red as her outfit. Just stay away from the tips of her sais.