JD is right about a lot of things. Don't bother with a recruiting service (although I don't know if they even exist for swimming). I had placed top ten in the country at USS Nationals in a couple events, so I aimed high when I was picking schools. I had a list of like 15 schools that I was interested in and sent letters to all of them, telling them about myself. I think a lot of schools already know, but if a person takes the time to write a letter and let them know that YOU are interested, that will reflect well on you.
Anyway, I sent the letters, and then I started speaking with the coaches. I talked on the phone with the head coaches, as well as the distance coaches (I swam the 500, 1000, and mile mostly) and got a feel for who I liked. I also did some extensive checks into the programs to see which schools I thought I had the best chance to succeed at. I then narrowed my list down to the schools that I wanted to visit.
I ended up taking recruiting trips to Michigan, Auburn, Cal-Berkeley, U of Arizona, and Stanford. Then it's a matter of just hanging with the guys and figuring out where you think you'll fit in best. I thought the Stanford guys were tools (no offense to any Stanford guys out there
) and knew I didn't want to be there. Auburn was (and still is) a big sprint school. Cal was cool, but I wasn't sold.
It basically came down to UofA and Michigan for me, and Michigan didn't have any money available and it was going to be like $30K a year with no guarantees about scholarships for later years, so I went to UofA. I then proceeded to smoke a lot of pot, not get very good grades, never swim as well as I should have, and left the program after a couple years.
It somewhat haunts me to this day that I didn't pick Michigan, because maybe things would have been different and I would have reached my potential. But that's neither here nor there. I wouldn't trade the life experiences (or friends that I gained) in AZ for anything though, because it helped me become the person I am today.
Post here or feel free to PM me with any questions you have about the process. It can be very overwhelming I know.