In the future I want to move up to mid and high stakes, but first I want to build a solid preflop foundation. I understand that at lower stakes players tend to overcall, play too tight, and 3/4-bet too little — which actually makes a GTO strategy very effective since you can steal the blinds frequently.
My problem is that I don't really know how to study preflop properly and couldn't find a video here that covers the topic well. I know you should learn the bottom of your range, and I found this video helpful for memorizing ranges: https://youtu.be/EC0nxNA4OHQ?si=1q0csbXfBvj5FMU0
But how do you handle mixed strategies? They might not be essential at low stakes, but since my goal is mid/high stakes I want to start building the right habits now.
The other issue is that preflop has so many variables — rake, sizing, opponent adjustments — which is overwhelming. If I try to simplify my ranges I'm worried I'll miss important combos like 87s, 65s etc. And if your preflop is off, your postflop will deviate from GTO as well.
So my question is: how do you actually study preflop? How do the pros approach this?