I'm an adult and I've been playing for a bit over 2 years on chess.com. My rating started at around 800. By playing thousands of blitz games and doing a little post-game analysis/opening review, I was able to get to 1400 in Nov. 2019. However, I struggled to push much farther this year. However, this month I started solving puzzles - maybe 20 per day or so - and gained about 200 rating points. It's crazy.
Are there any other levers like this one that a beginner should know about?