thats a good move to defend
How to beat 1.d4
well what type of player are you? there are loads of videos on youtube,
heres a list, slav, semi slav, kings indian defence, grunfeld, bogo indian, nizmo indian, queens indian, ( i suggest any of those , look them up and see which one of them helps you out, and against nf3 on move 2. just watch sam shanklands videos against passive queen pawn openings
, just click solution and pay attention to annotation below
The subjectively best way is to bring the game into Nimzo or Queen's Indian. But there are a lot of work there.
depends which style you prefer;
king indian or ben oni, or benko gambit . on other side queen gambit, queen gambit accepted, slav, holland... go through all of these and analyse+play lots of games to find out which style is most suitable for you.
I think the Grünfeld, Nimzo Indian, (Semi) Slav, Kings Indian, Ragozin are among the most fighting + sound openings against 1.d4. Hope this helps :)
i like king indian a lot and thing this is maybe best for black, and i appreciate it a lot and i enjoy seeing these games , but - i do not play it at all. it is not my style and i cant help myself, i cant make good scores. i studied a lots of king indian games, ideas and players, but it is just not my stile.
so to determine what is the best, you must play all of these...

PSA : The OP asked this silly question 6 years ago, and he hasn't been online for more than 2 years
LMAO Two additional years and he'll ask how to beat 1. d4 Nf6.
Possibly of interest:
First Steps: The Queen's Gambit by Andrew Martin
https://www.newinchess.com/Shop/Images/Pdfs/7652.pdf
The Slav: Move by Move by Cyrus Lakdawaka
https://web.archive.org/web/20140627104306/http://www.chesscafe.com/text/hansen151.pdf
Nimzo and Bogo Indian by Christof Sielecki
http://www.jeremysilman.com/shop/pc/Nimzo-and-Bogo-Indian-The-76p3910.htm
https://www.newinchess.com/Shop/Images/Pdfs/7361.pdf
Understanding the Queen's Gambit Accepted by Alexander Delchev and Semko Semkov
https://www.newinchess.com/Shop/Images/Pdfs/7536.pdf
The Fianchetto Solution by Emmanuel Neiman and Samy Shoker
https://www.newinchess.com/Shop/Images/Pdfs/9029.pdf
The Killer Dutch by Simon Williams
https://www.newinchess.com/Shop/Images/Pdfs/7499.pdf
Grandmaster Repertoire 11 - Beating 1.d4 Sidelines by Boris Avrukh
https://web.archive.org/web/20140627001415/http://www.chesscafe.com/text/hansen164.pdf
https://www.newinchess.com/Shop/Images/Pdfs/7156.pdf
I can't seem to find a good defence against d4, please help