Playing today I realized a big gap in my strategy is how I respond to/play 3bet pots. 1 player in particular started 3betting me very often as most of the time, I just folded.

I'm definitely uncomfortable in those pots as not sure how to gauge their ranges, or commit a bunch of my stack in a more marginal spot. (AJo facing a loose 3bet from someone in position on you, etc.)

My question is, if you know this is a weakness in your game, how would you go about improving it?

I can't really play online in the US, so can't move down in stakes and try stuff out. Would prefer to learn some drills or exercises I could use to play these spots better.

Ideas??

FWIW - I probaby don't 3bet enough either. So could use some drills to practice those situations too.