Advice for Modders
This page serves the same purpose as Making a Mod, except that all contributors may edit it.
Priorities
In the start, don't waste too much time worrying about things like your menu or a player model. Just get straight to mapping, because that's what ties everything together, and it's probably what most of your time will be spent on. Without maps, you effectively have no game.
That being said, too much attention to a given map can be equally detrimental. Many will tend to focus for too long on "perfecting" a certain map, as it were, making more and more layout and visual changes ad nauseam. While a level of quality control and an eye for detail is important, staying on one map for too long can slow development to a crawl, especially given the small development team size mods tend to have. In short: know when to move on. Perfecting everything is an impossible task.