How do I improve my opening?

My rating vs pretty good in live chess.
2000+ in blitz - play mostly
1550+ in rapid and bullet - don't play these formats much

My rapid rating may seem low, but the thing is I rarely play rapid. And I've beaten 1800-1900 rated players several times whilst having a continuous advantage. 

I'm good at middlegame and endgame, but in case of opening, I kinda suck

This has cost me severely, as I lost tournaments due to opening disadvantages.

So, how do I improve these?

I actually have the same question... But I have a idea.

Remind me to tell you my idea friend I must go now.

With an 100% on advantage capitalization and resourcefulness why would you need better opening

Well, bcz I don't want to give my opponent opening advantage and me to fight uphill all the time.

That logic, you want opening knowledge so you have the advantage. Better to play in the opening pawns on from the c to the e file to the 4th rank, the knights on th 3th rank, the bishops on the 2nd or 4th rank, the rooks on the 2nd and 1st rank and the queen on the 3th or 2nd rank. Then you have most of the control of the center.

Bleksvift you copying sussyguy you both are sus.

Try another strategy

Why are you just copying people's comments

When studying openings, you need to find an opening where you are able to UNDERSTAND the ideas for BOTH SIDES! Even if you only play the opening from the White or Black side, you need to understand the ideas for both sides. Memorizing doesn't do you anything. You get through the first 10 moves and then what? You have no clue! They play a different move in the opening, can you explain in words why it is inferior? I had a game over the board as Black maybe 6 years ago that went 1.e4 e6 2.d4 d5 3.e5 c5 4.c3 Qb6 5.Ne2 (instead of 5.Nf3) If all I did was memorize, I'd be screwed. However, from e2, the knight plugs up the Bishop. It does nothing to cover e5 (unlike the knight being on f3) if White tries to play f4, the moment he castles there are tactics on d4 due to the White King. So White has trouble sufficiently controlling the e5-square. I destroyed him. Was winning by move 18 and he resigned somewhere in the 28 to 30 range.

I "understand" the French, Petroff, Dutch, King's Indian (though don't play that opening any more), Torre, Trompowsky, London, Sokolosky, etc. I don't "Understand" the Grunfeld or Alekhine, even if I can spew moves from memorization. I am mince meat after that, and so I avoid both openings and any opening where one side has a massive, MOBILE, pawn center. The Kings Indian and French give White a big center, but it is a blocked center., not a mobile center. 1.d4 d5 openings lead to a static center, the Petroff or Exchange French an Open center. All of those I get. I hate the big mobile pawn center (Alekhine/Grunfeld). You need to figure out the types of positions that make sense to you such that you COULD play it from both sides, even if you choose to only play it from one side or the other.

No matter how you set your repertoire up, there will always be one opening you must play from both sides. For me, that is the French. 1.d4 e6 2.e4 d5 and 3.Nc3 or 3.e5 (as Black I also have to deal with 3.Nd2 and 3.exd5, but as White I would only play 3.Nc3 or 3.e5.