1 knee but toe.
The included angle between thighs and calves is not less than 90 degrees, that is, don't squat.
3 when squatting, bend the hip joint first, and then bend the knee joint.
The waist is always straight and the hips are upturned.
Put a few centimeters thick board or barbell on the sole of your foot.
6 Fully warm up, jog for a few minutes, then stretch the joints, then warm up the two groups, and gradually add a lot. Heavy weight training is not afraid of slow heat, but of injury.
7 After each exercise, kneel down and bend over to let the thighs relax completely.
These are the most basic common sense, but many people don't understand and don't study them. Without scientific training, joints will be damaged and disabled. At present, I hope you can reduce the amount of exercise, standardize your movements and establish good habits. When there is no discomfort in the legs, increase the strength.
I hope my answer can help you, and I hope it can be adopted in time. Thank you.