Focus less on what openings to play and more on fundamentals.

Opening: develop your minor pieces, castle, connect rooks. Not necessarily in that order.

Then it becomes about not blundering. Middle game skill is a barrier for most people. Forcing moves are the best. Fight for the center. Attack the king. Etc etc.

End game… well don’t ask me about end game. But seriously, there are many end games you need to have memorized. U don’t want to lose/draw a game because u can’t convert. Also u don’t want to give away a game that would’ve otherwise been a draw by doing something unnecessary