I do everything solo as well! But I have found I just can't do some things at all (I can only draw stick figures) and I use freelancers for these jobs. Sometimes tricky and difficult, but I have found several freelancers with which I have a long standing relationship, which really make things much easier.
I always start with a map, to get a general overview of the game world, and then I start writing. (I make RPG's as well)