I'm not sure if there are any books that speak specifically to buying preforeclosures, but buying in preforeclosure is not that different than buying any other property as an investment. Often it can get more complicated (sub2) than a straight cash deal if they owe as much as the property is worth, but JV with a savvy investor and they can help you through the deal. My first few deals as a wholesaler were sub2s. Not so much by choice, but because of their situation cash offers didn't work and sub2 did.
To the preforeclosure point, the best thing to do here is to buy a list a do a direct mail campaign to them. Send letters and / or post cards. Be persistent (mail to each lead multiple times). If you get a lead, go meet with the seller the same you would a normal distressed seller. Here in NC you get about 90 days from seller receiving their NOD (notice of default) to the auction date (which can easily be extended). As a noob, I'd steer clear of the auction steps like the folks above suggested. Unless you want to go with zero dollars just for experience.
Best of luck!