Like a lot of players I think initially I worked a lot on pre flop ranges. Certainly improved my play but after a while I realised it was only a small piece of the puzzle. You need more to be a good player. Decent pre flop raising ranges simply lift you off the bottom rung of the poker ladder, it is entirely possible to still be a terrible player with good pre flop ranges.
The other thing about pre flop is you need more than just a chart that
tells you when to open raise. Lately I've been studying and trying to think more about how to react in every seat on the table vs a raise or limp, with villain ranges/seat in mind. I'm trying to be much more positionally aware not just of my own position, but of any active villain's position and what it means when they raise.
Need to get past simply thinking 'Well they have a hand they think is worth raising, I have a decent hand, I'll call it, let's see what happens'. What we need to think is 'Villain raised from UTG+1, his stats are 16/12, but he'll be tighter early, therefore his range could be something like 77+, AT+ (maybe about 10%). This information, even when not perfect, is crucial to whether we should enter a pot or fold.
I find the best way to quickly imagine pre flop ranges of villain is just to think 'What would I be raising in that spot?'. If their HUD stats are looser than yours add a few hands on, if they are tighter, take a few hands out. Take notes on a few simple ranges after looking them up in an
equity calculator and keep than handy, eg what does 5% look like? 7.5%? 10% And so on.
Lately I've been working on understanding post flop hand strength a bit better and other post flop matters, eg board texture, ranges etc. My 3 Betting pre flop also needs work. Cardschat hand analysis threads are a great place to learn and post your mistakes and failures to be reviewed. I've also been messing about with equity calculators. And taking a fresh look at some post flop strategy relevant to the games I play, which lately has been mostly 2NL cash.
There is so much info out there for free, but a lot of it is poorly presented, or the focus is too narrow for it to be useful to someone learning (and can even harm your game if implemented incorrectly). There are so many situations that occur in poker, one of my biggest struggles has been coming to grips with the fact that there is usually not one easy answer to a lot of the questions we have when we are learning this game. So much is situation dependent.
With situational dependency in mind, I need to spend more time thinking about WHY a strategy is telling me to proceed a certain way, rather than just adopting that strategy in a certain spot like a copycat who is not using his brain. Gaining awareness that I can translate to other spots in game seems like a much better way to learn. For me, the struggle goes on, but hopefully I am improving.
Overall my biggest challenge is implementing the things I have learnt at the table. The clock ticks fast and memorising strategy is a huge challenge for me personally. I keep a lot of charts and notes handy, try to avoid using them every time, but do find they give me some confidence if I am unsure.