I've tried to force myself to work at least an hour at a time when developing Kaduria and it seems to get things done (slowly but surely), rather than those times when you start the IDE, look at the code for few minutes and then exit.
Returning to case of professions it's kind of silly business, because professions are built on top of skills (mainly), but the thing is I don't even know what skills there should be in total and how they actually work. You can always throw in some generic stuff, but it can become something you don't need later. It happened with some professions which there is no need since I removed hobbits from the game.
As always you should start small with data (or design if you want a fine name for it). My inability to build a solid RPG structure has certainly given me more problems than I actually need. But I guess the situation is not hopeless. The development process in this area is progressing slowly from fuzzy ideas to something more tangible.