Add-ons
Add-ons should have a specific focus on a workflow or set of related tasks. If a good high level summary of one cannot fit into a sentence, it should probably be split into multiple add-ons that can be bundled together.
Naming
The name of an add-on should reflect what it does but does not need to be overly literal. Simple add-ons with one or two features benefit from purely functional names, e.g. "Export to New Blend" or "Orient to Selected". More complex add-ons benefit from a branded name that gives at least some indication of its use, e.g. RetopoFlow. A great name is also one that's fun, exciting, or evokes the type of feeling a user might have when using the product. The word "Blender" is a bit of a legal gray area and should only be used at the end to say the add-on is "for Blender" and only if necessary.
Installation
It should be assumed that the add-on will be installed as a .zip file via Blender's preferences, and that the user should not have to go to Blender's add-on folder to manually edit or move any files.