Stuck at around 530 - 550 elo, how do I improve?

I have had this problem for about a month or so now and its getting a bit annoying. I am stuck around the 500 elo mark with my highest elo this year being 559. What can you suggest that I read/watch to improve to my chess game? 

If anyone is wondering, the opening that I play for white is always the queens gambit, centre game, or 4 knights (depending on opponents response to queens pawn) and the opening I play for black is usually 4 knights or kings indian.

Improving Your Chess - Resources for Beginners and Beyond.....

https://www.chess.com/blog/RussBell/improving-your-chess-resources-for-beginners-and-beyond

https://www.chess.com/blog/RussBell

Study the principles behind the opening moves as opposed to just simply memorizing the lines. Stick with simple openings that develop pieces and are easy to play. Openings at lower level should not be more than 20% of studying time. It's more important to focus on the middlegame which consists of positional ideas and a lot of tactics and combinations. The reason behind this is that, the goal of the opening is not to check mate immediately (although that happens, and a lot for beginners), but instead have a "playable" middlegame position. If your middlegame is very strong you can outplay your opponent even if you didn't do very well in the opening. However, it's very important to know the traps that occur in your opening. Also notice the amount of blunders that beginning players make and compare that to stronger players. That's why tactics is very important. Also it's important to know basic endgames. Endgames that are appropriate for the level. For example, it's understandable when a beginner doesn't know KBN endgame since the chances of this appearing in their game is so slim. However it's expected to know the KR endgame.

First thing you need to focus on is tactics, and not blundering. Do some sort of blunder check every move. This alone will add a few hundred points to your rating. This is the single biggest reason players under 1000 rating lose games. Focus on doing puzzles. This will help with building your calculation ability, and see both opportunities to get material advantages, or prevent you from losing material.

Here is an analysis of your last loss:

Your first big mistake is on move 9. Qxe7. This drops the knight on d5. You should have recaptured with the knight Nxe7. This would have prevented material lose. Your net mistake is on move 17 is your next mistake. You are playing too passively with the move h6. A much better move would have been Raf8. This would have created battery with your rooks, and can potentially lead to counterplay for you. If you play passively when you are down material then you will lose every time. This is because you are not putting pressure on your opponent. Putting pressure on your opponent can lead to you closing the gap in their advantage making it harder for them to convert on the advantage. Your next mistake is on move 20. playing b5 actually just drops your rook (your opponent did not see this, and therefore did not play it). This could have been prevented with doing a blunder check. Also if you need to get better at coordinating your pieces. If you had tried to coordinate them like creating a battery then the piece would not be left undefended as easily. Another reason that b5 is bad is because you over extend your pawns leave them vulnerable to just be captured. This allows them to become passed pawns which makes your situation worse. You would be able to trade them off if you don't play b5 if white decides to continue to push them. If you use those extra moves to create some counter play that would make them waist moves that did not do anything while your moves were with a purpose that can create advantages for you. Even if your opponent is still winning it will give you chances to either win or draw.

When it comes to your opening choices the Queens Gambit is the best of those, and is played at the top levels of the game. Center game is fine for amateur level games (I personally play this opening as white), but is an e4 opening not a queens pawn opening. If you are playing d4 d5 e4 then that is not center game. That is the blackmar gambit. Like Center Game it is fine for amateur levels of chess, but not master level. 4 Knights is an opening that white chooses. I believe you play the two knights defense (which white can choose to go into 4 knights). It is fine for lower levels of chess. There is nothing wrong with the opening, but there is always traps your tricks that you have to learn to counter. King Indian Defense is a good opening against 1.d4. For your opening as white I would suggest just choosing one opening, and stick with that one. That way you learn that opening, and how to play it. Trying to play multiple openings as white will just make you take longer to master the openings.

When it comes to openings at sub 1000 level it is best to stick with the opening principles, look for tactics, and do not blunder. This will get you to a playable middle game every time. When it comes to the opening that is what you should focus on instead of focusing on a specific openings.

When it comes to what you should focus on it is these things you should focus on:

1: Tactics (most important): do puzzles, and learn about them.

https://www.chess.com/article/view/chess-tactics (focus on forks/double attacks, pins, skewers, and discovered attacks)

2. Endgame basics: Learn overkill (two queens vs king, two rooks vs king, queen and rook vs king, queen and king vs king, and rook and king vs king). Be able to do these in severe time pressure. Learn the endgame principles.

https://www.chess.com/article/view/chess-endgames

https://www.chess.com/article/view/inch-by-inch-row-by-row

https://www.chess.com/article/view/basic-checkmates-the-queen-dance

https://www.chess.com/article/view/basic-checkmates-king-and-rook-mate

3. Opening principles:

https://www.chess.com/article/view/the-principles-of-the-opening

This is a good article to read. Some of it will be beyond your skill level, but there is a lot of good info in it: https://www.chess.com/article/view/after-the-rules-what-should-beginners-study-next

Hope this helps.

You could try studying the opening in more detail and perhaps learn another opening

I can teach you EXACTLY how to think during the game (opening, middlegame and endgame). Your chess understanding will never be the same and you will improve a lot. I charge $10/h, but if you can’t afford too many lessons, don’t worry. I can teach you a lot in an hour. Here to help if you are interested.

If you want to study by yourself, read ‘Logical Chess’. It is really instructive book. You have it on youtube as well: https://www.youtube.com/watch?v=0eTB7oHeRgM&list=PLUrgfsyInqNa1S4i8DsGJwzx1Uhn2AqlT