A1, my advice is to read as much as possible any material(s) you can find on your course of study. It's a common practice in my part of the world to return to class after some years to get your Masters. Sometimes the experience(s) pays in the long run. You just take it in stride and live for the moment. Remember the undergrad days, the fun and all. Don't think about the age gap. Dont feel ancient either cos you'll definitely meet people that you are older than by 2-10 years as the case maybe. Do not let this be a barrier to learning from them. With God by your side, and ofcourse, you'll ask Him for wisdom, you'll sail through and get your wish - to get the best grade!