Start early on project, things get crazy in the last week.
Try to get feedback from other people on the game because problems that are not apparent to you as the coder might be discovered by other players.
Divide tasks based on skill and interest, give people specific roles.
Use version control!
Keep game concept simple at first and scale up as you go, if time is available.
Get game mechanics working first and then work on making the game pretty. Playtests are useful here too because players give useful feedback on what visual cues are needed.