For the first couple weeks, simply stick to your class. Fold the class into your weekly routine. After class, hang around to ask the teacher about anything that may have caused you discomfort, anything that was confusing or unclear, or any questions or concerns that may have come up during the practice. Starting a dialogue with the teacher can deepen your relationship with the practice of yoga.
After a few weeks, begin some self-assessment. How has the yoga changed your bodymind? Do you find yourself thinking about the practice outside of class? If so, in what context? Allow yourself some reflection on what yoga has to offer you. Yoga has an amazing tendency to seep into your life off of the mat - it not only provides benefit to the practitioner, it benefits those people in the practitioner's life as well. See if you can attribute any recent life improvements to your yoga practice.
As you begin to witness the countless benefits of yoga practice, and you decide that yoga is something for you, it's time to begin your own personal home practice. Choose one or two of your favorite poses from class, and set aside 5-10 minutes each day to practice these asanas (you don't even need a mat!). 5-10 minutes doesn't sound like much, but it is a commitment that will bear many fruits. It may be helpful to set aside this time in the morning. This is the time of day that is the most peaceful in the environment and in your bodymind. Be sure to hold your commitment even on days when you don't "feel like it". This will make all the difference. Become completely absorbed in the breath for these few minutes, and cultivate joy in practicing your favorite asanas. This will provide a positive mindset, which will further motivate you to continue your yoga practice.
So get to a class, get on the mat, and make the commitment to yourself to carve time out of your busy life to dedicate to the most important person in your life, you.