One thing that always works out well is looking away or above the camera, which works out well for ol' Toddy since he serenades his own blades. This
one is the same as the pose you shown, only it's to a side and looking more upwards. With his gaunt face, looking up and to the side usually help make my face look longer and thinner. If you open your mouth slightly whilst doing it --like so
--, it can make the make up look more shadowed. The only time I knew of him smiling was when he was singing "My Friends", otherwise most of his character is very cynical and it shows in his face. Maybe even hold the blade up close to the cameras without looking it the camera (if they let you..) as if the perspective of the camera is of a persons. Like this.
Crazy eyes and all.
Needed to be known about method acting a character who has been acted out before is to be the role
of Sweeny Todd, not the actors portrayal entirely. Method acting takes staying in character even out of cosplay, which isn't necessarily needed, but for Sweeny Todd's character, I can imagine it being harder to stay in character even in photos so I'd have to get into the characters head... seeing how cons surround you with so much colorful atmosphere, and people.