You could just walk into the music store and say, "I wish to buy a guitar, and this is what I wanna play...." Thats what I did. :)
If the salesmen knows what he's talking about, and most do, they will point you in the direction of a guitar well suited to you. They will also let you try guitars out. Even if you can't play one, you could hold it, pretend your playing, that sorta thing, just get get an idea of how the guitar feels, and whether you like it or not.
By the way, since you don't need an electric, I would recommend a nylon string acoustic. They sound great, they are very versatile, they are easier to play than steel string acoustics, and are made of lighter woods, so they are generally less expensive. You could get a GREAT nylon string acoustic for the price of a GOOD steel string.