I think i've pretty much got my squat form down (after 2 months lol) but i have a question. When performing a squat, should you try and ensure that the bar moves straight up and down. i.e. i visualise that im using a smith machine.
I find that if i lean forward a little bit at the bottom of a squat it helps me drive upwards - but sometimes this will also take the drive away from my heels.