Do not aimlessly walk into the gym trying to max every time. Have a plan that gets you to your destination. Proper programming is the ultimate key to progression.
2. Build your plan around raw squatting
This seems obvious but it is not. The conjugate method and terms like "CNS burnout" have kept guys from earning their stripes doing the an actual raw squat. Box squats, zercher squats, safety bar squats, etc are all fine for SUPPLEMENTAL movements, but they should not be what you are basing your programming around. If you squat raw you need to get strong doing the movement you are actually trying to get good at.
3. Do pre-hab work
Anyone that followed my training into the Nationals know I was able to stay healthy by doing a lot of adductor work, which had been a problem area for me. Had I included leg extensions in as well, I believe that I finally hit the 650 beltless squat I have been chasing for a while now. My recommendations for keeping your tissue healthy are the good girl and bad girl machines (adductor and abduction), leg extensions, lunges, stretching, and of course the good ol foam roller.
4. Build bottom position strength
For the raw squatter this is paramount. Most raw guys will miss a squat because they can't generate enough power out of the hole, then the lift stalls at mid-point. If you build your bottom position strength your squat will jump. The single best exercise for this is the pause squat. The other great thing about the pause squat is that it will teach you to stay tight throughout the movement, and how to explode out of the bottom. If also should reinforce good technique. If your knees or hips hurt when you do pause squats, something is off. More than likely you squat too fucking wide or/and don't squat deep enough. If you look at the videos of my pause squat I sit all the way down, hams on calves. This is a full squat. And a full squat is what squatting is. There is nothing uglier than a high raw squat. Don't be that guy.
5. Be patient
Lifting is a marathon, not a sprint. I think I squatted 500 for the first time something like 10 years ago. So I've consistently put on around 15 pounds a year on my squat. Some guys progress faster than others. Your squat may move fast at times, and stall at others. Just regroup and give it another run. Rinse and repeat.
This shit is not complicated. All you really need to do is stay healthy and put in a lot of sweat in the squat rack. It will eventually happen for you, I promise. But you will have to earn it. People avoid squats for a reason. It's humbling and hard. But in the end you will benefit from the effort.
Remember, mediocre people are always satisfied with themselves. Never be satisfied.