Congratulations on your new baby!
Learning as much as possible ahead of time is the best way to prepare, so doing the class is probably your best way to get ready.
My top 3 tips:
1 - Learn how breastfeeding works - this will help you to understand what is normal (And what is not) and avoid some of the common pitfalls
2 - Know that your body is designed to nourish your baby when pregnant and after birth also, and that most mums can breastfeed successfully with help
3 - Find out where to get help if you need it. Not all sources of information and support are equal, and even some health professionals who work with new mums have only a limited understanding of lactation. Keep the ABA magnet on your fridge - 1800-686-268 - and get along to your local support group if you can. Find out if your hospital has lactation consultants available. If not, find one or two in your local area that you can call on if you need help. And don't delay asking for help if you need it.

Remember that every breastfeeding relationship is unique. Good luck!