If you are flexible enough, bring your elbows high and forward when you grab the bar. You'll create a type of "shelf" just behind the delt. Experiment with no weight. It should be rock hard behind the anterior delt. The bar should fit there nicely and comfortably (once you get used to it). Take a deep breath. Fill your chest cavity with air (sounds weird but don't inhale with your diaphragm). Hold the air on the way down and stay very tight. If you exhale on the way down, you'll lose it. Exhale on the way up.
Here's another suggestion, wrap lifting straps around the bar. I like to front squat outside the rack but there is nothing wrong with doing it inside if it makes you more comfortable. Anyway, grab the loose ends of the straps and get into position. This will alow you to get a comfortable bar position even if you lack the wrist/shoulder flexibility to get into the position described above. Front squats feel awkward at first. Don't give up. They're an awesome exercise that will really pay off in the long run.
Final thing, if you know any olympic lifters or knowledgeable bros that could help you out the first couple of times then I would strongly recommend asking for help. This is one of those things that is really hard to describe in text but easy to demonstrate.
