Understanding the Queen's Gambit Accepted by Delchev and Semkov is nice and succinct, I would highly recommend it. The authors present several variations for black, and the most concise version of the repertoire (which I have currently employed for the last year or so) is only a few chapters long. It's great, especially if you want to prepare for OTB play, as opposed to a more exhaustive reference manual for correspondence chess.
There is even some bonus material at the end to prepare you for stuff like the London System and the Hodgson/Levitsky Attack. It's definitely good to have something against the London, but thankfully you don't need a whole lot, and there are some great videos on YouTube that you can use to supplement.
GM David Smerdon posted a review here, maybe check it out:
http://davidsmerdon.com/?p=1769
First you need to figure out what opening you want to play against 1.d4.
Queen's Gambit Declined, Queen's Gambit Accepted, Slav Defense, Semi-Slav Defense, King's Indian Defense, Nimzo-Indian Defense, Grunfeld Defense, Modern Benoni, Dutch Defense, etc.