Study advice (short-handed online cash games)

Hey guys, I’d appreciate your advice on how to approach studying poker in my case.

Some background: in 2010-2014 I played micro-stakes online sit-n-go’s profitably for fun. I do understand most of the basic poker concepts. A few months ago, I started playing live cash games for fun with small losses which I attribute to getting back in shape and refreshing my theoretical knowledge.

Then I got invited to a private ClubGG club. There are about 50 active members. From what I’ve seen there, the field plays very poorly and I see a big winning opportunity there.

My challenge is that all my experience has been with full-ring tables. In this club, most of the action is with 2-4 players at the table. At times, it gets to 6-max and, very rarely, to 9-max.

So I need to get solid at short tables fast.

When it comes to preflop, I think free HU, 4-max and 6-max charts from pokercoaching.com would serve me well for now. However, I get confused post-flop since my full-ring-shaped understanding of hand strength makes me overly tight. And I guess I don’t bluff enough.

I plan to spend around $250 on learning resources. What resources would you recommend?