Play longer games, gives you time to stop and think. Do puzzles, tactics and end game tactics.
At your level, the biggest gains come from fundamentals, not fancy prep. Focus on not hanging pieces, playing simple opening principles (control the center, develop, castle), and checking for opponent threats every move. Blitz at 369 is mostly about pattern recognition, so do a few basic tactics daily and play slightly slower time controls when you can to build good habits. Also, review just one mistake after each game instead of everything. Improvement at this stage is very fast if you stay consistent. For structured learning, and guidance, have a look at the various classes we offer at our institute, Chess Gaja.
https://chessgaja.com/one-to-one-classes/
My highest rating right now is 369 in Blitz (My daily is 900+ bc I don't play much daily). Any tips for other beginners and me? Before you comment on this post, make sure your rating is at least higher than mine, maybe above 900+ Elo.