make sure that your back is straight, you butt is back, and your knees never come in front of your ankles. essentially, when you are down, you should look like you are sitting in a chair.
Here's a youtube video I found showing how this morning. www.youtube.com/watch?v=Hyjpz4jkjSQ
also - most people don't use their quads much from day to day. So if you weren't previously a runner, it is normal for your quads to be extremely sore for a few weeks.
Just a doctor in training who loves to sip tea, drink shakeology, read, knit, crochet, and exercise! www.homemadefit.com