Have a pose. Like a picture pauses a moment of time, you have to do the same. Most people don't pose for a picture flying through the air while doing a triple back flip saving a baby, but rather something more stand still. Such as Captain Morgan pose, the gun pose, the commander pose, the valiant pose, the pissed off pose, the depressed pose, and so on.
For start, try drawing something simple. Like a face, hand, person standing, or weapon. To advance your drawing you must improve the simple things first. Guns might be too complicated for now.