Julian Lavergne from France posted ways to get involved into lubuntu on the mailing list of the project and I am reposting his suggestions here.
This is a quick summarize for people wanted to help on Lubuntu. In general, all tasks will be documented on the Subteams pages:
Packages and Code: https://wiki.ubuntu.com/Lubuntu/SubTeams/CodingAndPackagingSubTeam
Artwork : https://wiki.ubuntu.com/Lubuntu/SubTeams/ArtworkSubTeam