The easy answer is.....always use FSS for at least one state. I also can't remember the last time I recruited without FSS. Potential is everything in this game, and if you don't know your recruit's potential, you very well might be stuck with a guy that's not improving very much for four seasons.
Don't worry about other messages (such as mid-level DII, or a top DIII level prospect) - those messages are always window-dressing.