I was over-the-top with my last 'review' (actually, these are more like comments for me.... honestly: If I were to actually write a review of anything, I would need a book to write it all in... I can't shutup)
In brief: V leg posing is a big no-no when you want to make a convincing posture. If I may be so bold as to recommend seeing one of my own submissions: sonicthehedgetrimmer.deviantar…
I also suggest steering away from front-facing presentation. That is, having all the characters facing the front as if posing for the picture. Have one facing sideways, turning his bip_spine and bip_head HALF way, and move his eyes to bridge the gap, to look at the camera. Take a look at some of the official character profile images, say, from perhaps Sonic Adventure 2, or something to see what I mean (Sonic seems to love showing the camera his butt )
As for finger and the triggers: standard gun safety and professionalism suggests that "don't touch the trigger until you want to destroy whatever the gun is aiming at" so I'd probably suggest this for a non-actiony piece, but even in an action piece, on any gun the index finger does not go that far into the trigger guard. Typically, the very tip of the finger (in SFM terms bip_index_3 or something) is what pulls the trigger. On some hands, like large fingered or large handed shooters may meet the middle of their "3" and "2" finger segments to the trigger.
Furthermore, as for Silver, that finger posture would be painful. For better examples to holding types of firearms, I suggest buying a toy pistol or if you have a real pistol on hand, hold in your hand and have someone take a picture of it (the gun should not be pointing at the camera, obviously). A 3/4th angle of the hand holding a pistol usually achieves the universal grip for a gun.