I main the QG, but honestly, probably don't know as much theory as I should xD. Below 1000, I think a lot of people don't really develop their pieces. Try to develop as fast as possible (Bb4, Nc3, Nf3, castle); a lot of the time you'll be able to bust open the center and have a winning attack.
So, as you know, queens gambit, may be the most popular gambit (due to the show). I don't really care about the show, but what are the main lines to it? (for white)
Here is all I know.
Feel free to add the main lines to it.