As I mentioned before, I'm not the best at posing. When I'm on my own, even if I know the character well, I'm not sure what to do with my hands, my face, my posture....etc etc.
It can be really difficult! Even if I have a great photographer like @yenra guiding me (he's the one who took these photos as well!!), I feel kind of stuck. It doesn't help that I usually choose flirty characters, which bring on a world of poses that I just don't know how to do! I may be a little flirty in real life, but this doesn't always translate to my posing for cosplay photos.
What I've found is that I'm much better at posing with friends! Not only am I more comfortable cosplaying a character when I'm doing it with a group of my friends, but I also find posing so much easier! We can use each other as inspiration, or, pose based on how our characters interact.
While I still think my facial expressions could use work, I will recommend to anyone having a photoshop done to get some friends to come along! They'll be willing to tell you when you look awkward and help you work it out by posing with you!
The cosplays pictured are from AKB0048; photos taken at Otakon 2013.
Photography credit (Images 1-3):