I've come to the conclusion that I'm at the point where it would be better for me to stick with a handful of openings I can know well as oppose to how I would normally just play quite a large range of openings. My question is how I would find out what openings suit me since I plan to constantly play them because honestly with so many openings it feels difficult to choose. For instance I can't decide whether I prefer e4 or d4? Also I don't really have an "official" repertoire against openings that aren't d4 or e4 such as g3/g6 or b3/b6 openings, is this an issue? I normally just follow opening principles (control the center, develop etc.) to get by those openings.
Yes, it is better if you concentrate on just a couple of openings. Even though it feels difficult to choose, you should know if you like closed positions (then, generally speaking, play 1. d4 as White, and choose e.g. French and the King's Indian as black) or open positions (when it makes more sense to play 1. e4, and e.g. Sicilian and the Grünfeld). If you have no preference, check your results - play the openings which you were successful with in the past.
Although, to become a better chess player, you need to practice all types of positions. (But not all openings.)
To answer your last question: if your opponent plays an 'odd' opening, you should indeed be fine if you develop along the general principles (but watch out for sudden tactics).
Here's what you might consider a slightly off-the-wall idea for figuring out what kind of opening you might enjoy playing...
Get a source of games which will afford you a plentiful variety of openings. I use a games database, but take your pick.
Find some random way of selecting 100-200 of these games. You might pick the month of July in a random year; whatever is easiest for you. Try to make the other particulars as varied as possible, but choose games played by players whose ELO rating was at least 1800. Those will offer a few advantages over games played by lower-rated players:
- They will be full of the ideas that are characteristic of those openings
- They won't be cluttered by simple blunders that teach you nothing about that opening
- They will demonstrate the variety of positions (or lack of it) that comes out of each opening
- They will generally be true to the nature of the opening (strategic vs tactical, slow maneuvering vs immediate contact, melee combat vs constant attacking against constant defense).
Then, start playing through the games fairly quickly. Try to keep in mind that you are getting a feel for the opening, not trying to memorize or recognize anything. Ignore any variations, but if you stumble on a game you think might be useful or fun to analyze, tag it so you can return to it later. You shouldn't spend more than 10 minutes on the play-through for each game, and more often than not, it should take less than 5 minutes.
Bias your play-through time towards more unfamiliar openings with positions you aren't used to. Make sure you hit a couple of Trompowsky's, Budapest Gambits, Smith-Morra Gambits, Hedgehogs, Two Knights Tangos, Sokolskys, Grobs, Dutch Defenses, Snakes, Moderns, Wades, Veresovs and so on. This isn't a comprehensive list of relatively unusual openings, of course, but if you're missing one of these openings completely, your selection may be too homogenous. Go get some more.
If you find yourself playing through a game that's still very similar to a prior game, skip it. You can also just look at the ECO codes; if you have more than 5 of one code, skip the remainder.
If you find yourself playing through an opening you know, skip it. If you find a game that's out of book from move 3, skip it (you'll need to use some chess software and an opening book to make this efficient, but you can do it with an ordinary opening theory manual). These games won't contribute to your understanding of what kinds of new openings you might enjoy playing.
For each game you play through, play it through once as White, and then once again as Black. Stop at move 20, and don't look at the remaining moves.
Try to notice how you feel while you're playing through it, and how you feel about the resulting position. As White, and again as Black, were you: Excited? Bored? Anxious? Suspicious? Angry? Interested/Curious? Add corresponding tags to the games so you can find them again, preserving the color information. Note that "Confused?" isn't one of the options; it's fine if you're confused by an opening, when you first encounter it. That's a good place to develop more chess muscle!
Next, play through the games that made you Excited or Curious. This time, stop at around move 22 in each case, and put about 5 minutes' think time into selecting a move for the color who's on move, without looking at the actual move played.
How did you do? Compare the actual move, your selection, and a chess engine's preference. Did you do as well as, or better than, the actual player? If so, this might be a good opening for you to try first. If not, but the opening made you excited or curious enough, the fact that you didn't come up with the best move just means it's not as good a fit with the openings whose ideas you already understand - you'll just have to put more work into getting to know the ideas for these new openings.
You can ignore those games that gave you negative vibes, if you want, and I wouldn't blame you if you did. But consider that you might be able to use them to teach yourself patience, stamina, tenacity, adaptability, tolerance for discomfort, and a host of other character attributes that will make you much harder to beat. Try to "guess the move" for one color as you play through the remainder of the game (I prefer to choose the winner's color, but I play the loser's side too, occasionally, just to see if I can save the game). The experience will pay dividends, even if you don't use the game in opening preparation.
So, none of this work will be wasted, whether you choose to learn a particular opening or not.