I've read the book and watched a lot of videos of others squatting and I feel I'm doing largely ok but I've recorder video to check, because:
1. Others will see better if I'm doing something wrong
2. Albeit I'm progressing good on basic starting strength program, I still feel low back muscles pain between the exercise - days as if those muscles are over-loaded and could not restore. I'm trying to understand why and last time I noticed that going up in squat I can do it differently - pushing my butt up basically with my legs OR pulling it with my back. It might be I'm doing it with my back, therefore the pain.
Get squat shoes
Toes out 30-35 degrees
Do 5 workset reps
Donīt go just down with your ass. Shove your hips back at the beginning of the decent
Change the back angle from vertical to horizontal
Reach proper depth instead of stopping above parallel
In english: Read the book
Sorry, did not read about proper filming before.
Thanks for feedback, I see what I can change now.