If I get asked to take a photo with someone, I usually then ask how they want to pose, and offer up some ideas. This way, I can say 'I'm not comfortable with that' if they come up with something crazy (not that it's happened to me!), or I can warn them if a particular part of my costume is easily damaged (which I have done before).
I've found it makes for more fun shots too-- I'll pose like I'm fighting the other person when I'm in my Kyoshi Warrior garb, whereas I might curtsy to the other person when I'm in my Twilight Sparkle ballgown. It's an added chance to be in-character, and people tend to love it!
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- Rose Lalonde "Glow" Tier (Homestuck): 95% (Detailing) Otakon 2014
- Fancy Mewtwo Gijinka (Cowslip Gijinka): 3% (Planning) Otakon 2014
- Secret Cosplay (???): 1% (Planning) Katsucon 2015
- Magic Armor Link (LoZ: Twilight Princess): 15% (Patterning) MAGfest 2015