Mainly just playing lots of hands with a variety of players, both stronger and weaker than me.
Mostly live, but during the pandemic I played a zillion hands in private online games. That was great to get so much volume, though I think most people play more carefully live than online as a general rule.
I think I learned faster than I would have from both my live and online volume because I was also studying — reading books, watching videos, listening to podcasts.
And thinking a lot about hands I’d played, rather than just forgetting sessions after leaving the table.
Last thing — and this may seem excessive to some — for about a year I kept notes on the two main games I played in, including results and short profiles on the regs in each.
I found this valuable in many ways, such as observing general habits and specific leaks I’d spotted in each person’s play. I’d also note questions I wanted answered. (Ex: What does it mean when this player bets big on the river? Do they always have it? Or do they sometimes bluff missed draws etc.?) So in future games I’d keep an eye out for those specific situations so I could better understand how they played.
It might seem silly, but forcing yourself to write down things you’ve seen (or think you know) makes it harder to bullshit yourself. I think Jim limps too many hands preflop, and Bill bets smaller when he’s bluffing… Do they really? If I write it down, I remember it more, and as more likely to actually watch for and test my theories than if I just kind of think them in passing.
After a while I’d pretty thoroughly profiled the key players and there wasn’t much more to track. It was in my head and I’d notice if my profiles were accurate, or if someone seemed to have altered their play. Not a perfect science, but a valuable exercise.
Now when I play against strangers in a new private game, or a casino, I have a couple dozen player archetypes to work from rather than just assuming everyone is an “average” unknown. If I see someone doing certain things in the first few orbits, I might say, “Oh, this guy’s play reminds me of Brian from my Monday game,” or whoever. Then use that as a baseline assumption and adjust as you get more info.
I can’t say I’m a crusher as a result, but definitely a much better player than I was.
Right now I’m just getting back into the game — I’ve only played three times in six months — but I need to get back into studying.