SHB pictures 

Here's what I suggest makes a good SHB picture:

Follow the fair use criteria, especially the Images that cannot be fair use guidelines. These supersede all the following criteria. Also, source your images fully (including all applicable from issue/page/panel, scan source, web source) and give a fair use rationale.
Ensure that the picture clearly shows as much of the character as possible:
The ideal image is a full-body, three-quarter picture of the character standing straight with no background, with a facing-the-camera or profile picture as the next-best.
If a full-body shot is unavailable, the picture must show the whole of the head and torso (or the equivalent for non-humanoid characters).
Visibly contorted poses should not be used under any circumstances.
Pictures which hide significant areas the character in shadow should be avoided (exceptions apply only where the shadow is itself part of the character's look - e.g. Raven.), as should pictures where blur or distortion effects are applied.
Colouring should be neutral - pictures which have a heavy colour cast, or otherwise depict the character with false colours should not be uploaded unless the cast has been removed first.
Heavily stylised art should only be considered for use when the character is closely associated with the style to the exclusion of less extreme styles.
Pictures which have more characters and/or objects than the subject of the article should only be used if the subject is the most prominent object - editing the picture, by cropping, obscuring and/or painting out the other characters may help to ensure this.
If the character has a clearly-defined primary costume (e.g. Superman), a picture of this should be used. Otherwise, the most recent ongoing costume of the character should be used.

Hopefully, you can see why I consider the Colossus and Juggernaut pictures (in addition to the earlier Turner pictures) Not Fit For Purpose. -