Choose a use tactical, varmint, across the course, benchrest, FT_R etc. This will give you an idea of what action, stock, caliber, barrel. Figure a budget you can afford to double up on quick. Do a lot of reading in places like accurate shooter, THR and other sites. If you aren't a great machinist with access to good equipment look for a gunsmith who builds such rifles...
I think Midway and Brownwells have some videos on Utube about building off Mauser 98 actions using their hand tools for truing barreling and reaming etc.