You do not need to toughen up your nipples, that's an old wives' tale. Best thing you can do is first, cultivate a good attitude--you WILL breastfeed your child! Hang around here and read, read books like "So That's What They're For," make sure your family and friends know you're committed to nursing and spell out for them how they can help you--make sure they know formula isn't allowed in your home, nor bottles. If you even think the baby needs to nurse in those early days, they need to give you the baby back to nurse, no questions asked. They can help you by bringing you drinks, keeping you supplied with reading material and/or movies, bringing you snacks, if they feel like they should be helping feed the baby. The most important tools to bring to the table are: your breasts, your baby, your knowledge, your attitude, and the attitudes of family and friends.
Know that it probably will hurt and be difficult for the first month or so. There will be days you want to give up. It will be SO worth it, though!
Congratulations on your upcoming arrival, and best of luck!