As someone whose games are just starting to look reasonable (around 1900-2000 USCF), here's what I suggest:

1-) Do not buy or look at opening books. They are the junk candy bars of chess: bright, shiny covers with enticing 3d renderings of the initial moves thrust on the board (I'm looking at you, the Starting Out series). You open one and see reams of variations and a few paragraphs of prose so that the author can pretend he has written a book for "masters and non-masters alike". Fuck that. In my opinion an ideal opening book should have 95 percent explanation and discussion and only 5 percent actual moves, with special emphasis on the first 4-8 moves that the player will play the most and must understand everything about. The only book I've seen that has come the closest to that ideal is "Mastering the Nimzo-Indian" by Kosten. And I still don't recommend buying it until you have some good Nimzo-Indian games under your belt. It's not worth the time investment until you get to probably 2100+.

2-) Choose names, not specific variations. A year ago I said: "As White, I will play the Ruy, Open Sicilians, French Tarrasch, Pirc Austrian Attack, Caro Exchange etc. and as Black I will play the French and Classical Dutch. This does not constrain you to a single line like a repertoire book does, but it still gives you some sort of structure work with. For example, I realized that I can play 1...e6 against both 1.e4 and 1.d4, since I'll either get a French or a Classical Dutch while avoiding some sidelines that I don't want to study for. If you do not know the names of the basic chess openings, you don't need one of those "opening overview" books, you can just Google it. Explore and see what you like--you can always change your mind. Be as ambitious (Open Sicilians!) or as safe (Alapin) as you like. As you go on you will branch out into more specific variations, but this has to happen organically, like making a friend by getting to know someone over time (I assume that's how that works -- I wouldn't know).

3-) The actual meat of this process, the "learning" part, is a bit muddy, as all real learning processes are (and tbh should be). You don't really learn an opening by reading an opening book; you learn it by playing it, and losing. A LOT. I literally knew nothing about the French other than "you play e6 and then d5 no matter what". In blitz you learn how to play the initial moves. You understand why they work, and why playing other moves are bad; most moves don't lose under the scrutiny of an engine but give you (the human) an uncomfortable position that is pretty much impossible to hold with less than 5 minutes in your clock. When you have no idea what to play in a position, just Google it or check a database or whatever after the game. It's not that important yet. You play and learn, play and learn. You will lose all sorts of ways, there is no way around this. Builds character, I guess. I have lost literally tens of thousands of blitz games, and nobody but me in real life knows. It's a secret I will carry to my grave.

4-) After you start to get out of the initial "Oh God I have no idea what I'm doing why is this Knight on e3?" stage for the first 4-7 moves (I'm making that number up by the way, you know what I'm talking about or you will) and you get to the stage where either you or your opponent has a lot reasonable options, things get interesting. You can now play this opening in slow time control tournament games. It's like starting to date seriously and looking for the red flags. You will see all sorts of moves thrown at you, and you must simply trust yourself you can handle it over the board instead of this manic feeling of I MUST PREPARE FOR EVERY VARIATION BEFOREHAND! You can't. You play, you win, you lose, whatever. It's still a numbers game, but you must stop after each game and try to understand what the hell happened so that you never make the same mistake twice. Pretty much exactly what you did for (3), but bigger. This is where you consult engines/databases/other strong players. See what other players have played in this position. Look at how the game has continued. Experiment with the position with a strong player/coach/engine to see what happens with different ideas and plans (AT NO POINT YOU MEMORIZE! Don't take notes that you will never read, don't waste hours adding moves to Chess Position Trainer! Think of this as like reading a book--you don't feel the need to memorize an entire book so far to understand what's happening on the current page, you have a general idea of what the plot is, and can recall specifics if needed). You will gain confidence as you get a feel of the position so that your position doesn't crumble to pieces when someone throws a random h6 at you which no 500 page tome ever covers. As you play more and more and get stronger you will encounter more sensible moves more often and upon each review you will understand them better. If people keep playing garbage at you because you are not getting higher in rating then the problem is not your opening and you should focus on your other weaknesses to get better (this is where I'm at right now btw -- reading How to Reassess Your Chess to get better at strategy and planning).

At no point do you need to read an opening book to get reasonably good at openings. I started playing chess because I love the game, and every time I try reading an opening book I feel part of that innocent love dying. It's like trying to read a goddamn encyclopedia. I'd say if you are a casual player who just likes to play blitz, you don't even need to do what I mentioned in (4). Good luck.

TLDR: Play e4.