Make application name formatting consistent (avoid using Amaroks, do use Amarok's).
For screenshots and other images, .png format is preferred. The Upload page lists the file types that are acceptable. 16px.
Remove all non-printable characters from image names.
Consells i suggeriments
Some Preferences that will help -
If you don't have  links against the sections, open your My Preferences (in the Personal Tools section of the sidebar) then look for Editing and in the Advanced Options set Enable section editing via  links
While you are in those settings, enable Show preview on first edit - while you are editing you can glance at the original display for reference
The default display is to show the preview first, with the edit box below. If you prefer the edit box at the top you can change that setting in the same place