I would personally stick to learning a few e4 and d4 variations and maybe the English Opening, though I didn't see it much at lower level play. I am also adding some fun, fairly solid variations if you wanted try the more obscure openings
Ruy Lopez
1. e4 e5
2. Nf3 Nc6
3. Bb5
A personal favorite of mine, especially the Rio Gambit Accepted line 1.e4 e5 2.Nf3 Nc6 3.Bb5 Nf6 4.O-O Nxe4, but in general it can create early control of the center and can lead to a strong position with an active bishop or forcing black to double pawns
Not my preference, but I used to see a lot of the Giuoco Piano
- e4 e5 2. Nf3 Nc6 3. Bc4 Bc5
and the Giuoco Pianissimo
- e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. d3
I wouldn't stress studying this one
Sicilian Defense
1. e4 c5
It's rare for me not to see this opening.
Sicilian Sveshnikov
1.e4 c5
2.Nf3 Nc6
3.d4 cxd4
4.Nxd4 Nf6
5.Nc3 e5
6.Ndb5 d6.
It gives a menacing knight position to white, but allows you to prepare your pieces for development and gains a general grasp in the center
Sicilian Dragon
1. e4 c5
2. Nf3 d6
3. d4 cxd4
4. Nxd4 Nf6
5. Nc3 g6
Can create very aggressive and constricting pawn marches for white and a fianchettoed bishop and free queen for black. This is very aggressive and loads of fun to play
English Opening
1. c4
A very flexible and reliable opening if you are well studied into it.
King's Gambit
1. e4 e5 2. f4
A sacrificed pawn for quick development. What's not to like
A few others you could also look into are the Pirc Defense, Indian-Defenses, Queen's Gambit, Caro-Kann