One of the most vital strength training compound exercises you can (and should) perform is the squat. And though there are all sorts of versions, there are some ways to perform it incorrectly, which can lead to serious injury.
I am reading a good book called, Strength Training Anatomy (third edition), by Frederic Delavier. One of the biggest things I have learned is that one of the keys to being successful at the gym is ADAPTING TRAINING TO YOUR MORPHOLOGY. In it he explains why short-limbed people can execute the squat with relative ease, versus a long-limbed person that can succumb to failure if executed improperly.
While there are TONS AND TONS AND TONS of strength training gurus and videos online, especially YouTube, my main go-to is Rob Riches. I like his style, the way he explains things and his lack of perfection-in-14-days-or-less diatribes that so many guys promise. He cuts through the nonsense and gives you the basics.
Top 3 Tips I Learned:
1. Keep ankles flexible--not loose and not rigid.
2. Do not allow knees to stick out further than your feet.
3. Stretch to avoid the "butt-wink." Click here to see what I mean.