As a group fitness instructor I see a lot of people doing the same thing at the same time. That way you really notice the little differences, little variations people create to make things easier or because they don't fully understand what they should be doing and which muscles they should be using. There are things that I see happen over and over again so I decided to hand you a little tip, a suggestion if you will. Just one at a time so next time you're in your workout you don't have to think of a million things at the same time and can't get a single one right because it's too much.
Today my suggestion is on squats. It's very simple: keep your knees behind your toes.
Why? Several reasons. The first one is that if you push your knees forwards when you are doing squats you put a lot of pressure on your knee joints. They don't like that. There are all kinds of things in that complex joint that can tear or get irritated and inflamed. If you often get sore knees after doing squats you are probably pushing your knees forwards and should keep an eye on them.
The other reason has to do with efficiency. If you move your knees forward you shift the weight off the heel of your foot to the front. When you push up in your squat you want to activate the back of your legs and mostly your butt. That's why we do squats after all, for strong legs and a nice firm butt. You want to be able to squeeze that butt and you can only do that if you push from your heels. If you have been squatting for a while and are not making any progress, this could be why.
How? I think I already mentioned that. Keep your weight on your heels. That's the most important thing. You can check if your weight is to the back my lifting your toes. Not much, just enough to see you can. That's all. What you also need to do is stick that butt back! You're at the gym. If you still look sexy after your workout, you haven't been working hard enough. So forget about looking silly with your butt sticking out. You will look a lot sillier using poor technique and even worse when you've been coming there for ages and still haven't booked any results. So push that butt back before you go down. Trust me.
I hope this helps. And yes, at first, if you make this change, it will get harder. But that's the whole point. If it's easy, you're not getting results and that's what we're here for after all. Else we could just stay and home and watch TV. Let me know how it goes.
If you have any questions on technique, you can always ask me. I don't know everything but always try to learn new things so if I don't have the answer I'll try to find it for you.
Have a good day!