Hip escape! Also known as shrimping. You're going to get put in all kinds of bad positions, and you should focus on getting back to a neutral position like full guard or half guard. Hip escapes will be your best friend, so drill them (there's no such thing as too many).
You will also find yourself in half guard a lot, so find a couple of sweeps that complement each other (i.e. if one fails, you can transition to the other easily, rinse, repeat).
Many of the more experienced students will opt to pull guard on you when you roll, this is to help you develop your guard passing. It's up to you to learn the different types of passes, but a good place to start would be the Under Pass (MTS Ep. 5, 15:17 and Ep. 11, 28:17 demonstrate this technique and options from it).
Those are your three commandments: (1) Develop good hip escapes to recover guard; (2) Become proficient in at least two half-guard sweeps; (3) Learn to pass your opponent's guard.