Your accomplishment should primarily focus on the aquisition of a new skill (e.g. I filed my first bug) or the completion of a new experience (e.g. I sent my first email in Thunderbird).

Accomplishments should represent a piece of user's activity that is worth rewarding. Accomplishment "Use GNOME shell instead of Unity" does not reward user's activity, but his taste - definitely avoid that sort of trophies.

Accomplishments shouldn't cause worthless activity, nor be based upon traffic, nor be based on numerical achievements. For example if one was "Filed 10 bugs" people would just file worthless bugs, instead concentrate on the effect that the trophy would have on the project. Accomplishments should be never based on meaningless traffic, like "Posted 500 Forum Posts".

When you write the documentation for your accomplishment, you should always assume the reader has no knowledge of the accomplishment or the software and technologies involved. Use the 'summary' field as an opportunity to explain in detail what the accomplishment is, explain any jargon.

Accomplishments are exciting and positive opportunities; the tone and language we use in the documentation should be friendly and encouraging.Accomplishments should either be great fun, or provide entertaining challenges for the user. Who would want to waste his time accomplishing "Be an active commentator on all Ubuntu related blogs"?

Accomplishments should be family friendly. Leave out any swear/curse words or naughty language/jokes.

Optionally, Accomplishments should nudge people to do things that are good for the community, even if they're not fun. Things that encourage maintenance of things that are out of date or cleaning out old information should be encouraged as they help keep resources relevant.

One of the functions of accomplishments is encouraging users to keep learning Ubuntu. Although this rule may not apply if you are creating a set of accomplishments for your game, this is quite important for Ubuntu accomplishments. Think how much might a newcomer learn reading the description of "Became a LoCo member" accomplishment!