Never start trying to fill in other's roles. If you're a gunner, don't go all the way up to another deck to repair the hull. Stay away from the hull. Only repair anything if you're asked to, or if you're far away from enemies. If you're an engineer, don't get on to the heavy guns (except on the Galleon, but that's another matter). You'll probably have a light side gun assigned to you. Also, if you're the secondary engineer on the Pyra, for example, never help the main engineer until asked. You're making a much more important contribution to the team by staying on your gun. Also, buffing is a minimal priority. If you're on a Galleon and a ship is sitting in your broadside, don't go buffing the engines. That's just silly.
Oh yeah, and don't take lesmok for the field gun. I'm not sure where people get that weird idea.