What is the best way to study the queens gambit opening?

What is the best way to study the queens gambit opening?

Via one of the many published books on it, board, and pieces.  You will learn a lot more that way than watching some stupid Video or clicking the mouse on an ebook.

Why do you think that having a real book with a board and pieces more useful than an e book and a pgn file where you input the moves for example

Study grandmaster games with it. Example:
https://www.chessgames.com/perl/chessgame?gid=1937841 

Sorry for the lengthy response, but do read through all of it.  It illustrates important information about studying chess and improving.

Because when you study an opening or tactics or endgames or game collections, using a board and pieces does the following that using an ebook does not do:

1) Using a board and pieces has been proven to be more beneficial to working on visualization skills, using a 3-d board instead of a 2-d screen.

2) In this case, learning an opening, a book might give a diagram maybe 2 or 3 times throughout the game.  Let's say the first diagram is at move 14.  Until you reach move 14, every time you analyze a sideline, assuming it is more than just one move, pointing out some blunder, when you get done with that sideline, you will be forced to reset the starting position and go through the motions again, which will re-drill the ideas.

Example - Let's say you are looking at a beginner's opening book on the French Defense for Black, and currently you are on the Chapter on the Advance Variation.  You set up the board.

You move the pieces 1.e4 e6 2.d4 d5.

Because it is a beginners book on the French, it mentions that White's e-pawn is threatened, and he needs to do something about it.  He can protect it, Advance it, or exchange it.

3.e5 

White advances the pawn, gaining space.  But it does take all pressure off of the d5-pawn.

3...c5

Black expands on the queenside, and puts pressure on the d4-pawn.

4.c3

White can also play 4.Nf3, but here, after 4...cxd4, without the ability to recapture on d4 with a pawn, could potentially make the e5-pawn weaker.

4...Nc6

Black continues to pressure d4.

5.Nf3

White adds protection to d4 as well as e5.

5...Qb6

Black continues to press on d4.

6.a3

This is White's main line.  The idea behind this move is to expand on the Queenside with b4 and then play Bb2 to add more protection to d4.  A major alternative is 6.Be2, looking to castle to safety, but with every move of Black's pressuring d4, this is not so easy.  For example, after 6...cxd4 7.cxd4 Nh6, 8.O-O? would be a major error.  After 8...Nf5!, White must lose material.  The d4-pawn is attacked one more time than it is defended, and after 9.Be3, the only way to protect it again, the b2-pawn hangs, and the Queen cannot get trapped in this case.  Therefore, White must play 8.Nc3, but after 8...Nf5 9.Na4 (or else d4 or b2 will hang) 9...Qa5+ 10.Bd2 Bb4 11.Bc3 b5! 12.a3 Bxc3+ 13.Nxc3 b4 14.axb4 Qxb4, Black gets an excellent game.  This is why White plays 6.a3 instead.

OK, so you have read the above content, and you have gone through the 6.Be2 sideline.  With an e-book, you just click the back button to move 6-white.  That does not really help you at all.

With the book, board, and pieces, because the first diagram in the book for this game is not until say, move 14, you have to reset the board, and replay 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Nc6 5.Nf3 Qb6 6.a3.  What doing this does is it re-drills the ideas you learned previously.  You should be saying to yourself what is going on each move.  Quickly in this case, yes, but you should be rethinking the same thing.  1.e4 e6 2.d4 d5 3.e5 c5 (attack d4) 4.c3 (protect d4) Nc6 (Attack d4) 5.Nf3 (protect both central pawns) Qb6 (be a pest and attack d4 again) 6.a3 (based on the explanations of 6.Be2 and the problems with d4 and b2, White is looking to play b4 and Bb2, where there is no hanging pawn on b2 and he can continue to protect d4.

Now we are at Black's 6th move.

6...Nge7

In the next game, we will look at Black's major alternative, 6...c4.  The idea behind 6...Nge7, like 6...Nh6, is to go to f5 and pressure the d4- pawn.

7.b4 cxd4

Taking the d-pawn is better than taking the b-pawn because after 7...cxb4?, White has the extra option to recapture with the a-pawn instead of the c-pawn.

8.cxd4 Nf5 9.Bb2

After the alternative, 9.Be3, White has to watch out as there are many ways to go wrong.  For example, after 9...Bd7, the natural looking move 10.Nc3 is a blunder!  After 10...Nxe3 11.fxe3 Nxb4! 12.axb4 Bxb4, black has an excellent game!  If the Knight ever falls, Black is up 2 pawns for nothing, and to avoid dropping the Knight, White is stuck putting all his pieces where they don't want to be, likely including his King to d2.  Black is better here.

Now I think you might get the drift, you reset the board, going again through the motions to get to White's 9th move, re-drilling what you already learned.  Don't just regurgitate the moves.  Regurgitate the ideas!  This is how you understand and not just memorize.  Quickly clicking a mouse with an ebook loses this drill.  One can claim they do the drill anyway, but even if they do, they probably rush it and do it wrong.  At a board, you are forced into it!

This goes for more than just openings.  This goes for studying GM games.

Let's say the author provides diagrams at moves 14, 23, and 38.  By the time you get to move 14, you have likely gone through the motions enough times that you can reset the position in the diagram after analyzing say, an alternative move for Black on move 16.  By the time you get to move 23, you have gone through the motions from moves 14 to 22 enough times.  The middle game is no different than the opening from that aspect.  You are going through the ideas.  Black played this 16th move to prevent White from doing X that the other move allowed, etc.  Something that once again an ebook or video with not force you to do.

When you are in Algebra class, and you are learning the quadratic formula, does the teacher assign 1 problem or many problems?  Going through the motions once you may learn something, but retention levels are low.  By making you do it again and again, like the 10 math problems instead of 1, retention levels are higher.  Same thing goes for learning openings and middlegame concepts in chess.

I would recommend trying the opening out without learning not to get a feel for it. You may play horribly but that’s ok. Then you could try to learn it all from scratch but having someone else explain the ideas to you will save you a lot of time and can be more insightful than if you did it all by yourself.

I do recommend Lars Schandorff’s book on the Queens Gambit which I made a study on or use whatever free resources out there if you choose. Also try to use @ThrillerFans advice as I would have had an easier time remembering the ideas if I did use a 3D board instead of using the screen