Here are the essential items you need to successfully breastfeed: your breasts and a baby. :-)
While it's good to get a lot of advice, and I'm sure there is some in the answers before and after mine (although I haven't read any, so, please, nobody take offense!), the best thing you can have is confidence in your own ability, a desire to breastfeed (which you already have), and mental images of the right way to put the baby to the breast.
Often in our society, women rarely see other women nurse -- any baby-feeding in public is done with bottles. Breastfeeding is different from bottle-feeding, and not just in the type of food (real baby milk vs. artificial denatured processed cow's milk) nor in the type of packaging (bottles vs. breasts), but in the way you hold your baby at the breast. Bottle-fed babies are typically held facing nearly straight-up or facing outward; breasts aren't designed to turn that way -- babies are supposed to be snuggled into the breast. Also, take off your shirt and bra, and go look in the mirror; notice that your nipples are not "front and center" but actually angle off toward the side -- toward your arms. This is the right way for them to point; but often breastfeeding women tend to twist and turn their breasts trying to feed their babies as if they were bottle-feeding, with the nipples turned more toward the front or the center of their bodies.
My best advice: if you haven't seen many women breastfeed, take the time to seek out breastfeeding women (your local La Leche League meeting should be a good place to start) and watch them nurse. If you can't, or it makes you feel uncomfortable watching another woman's breast as she latches on her baby, then get the book Breastfeeding with Comfort and Joy (http://www.BreastfeedingWithComfortandJoy.com) and immerse yourself in these beautiful and positive breastfeeding images, to get yourself on the best start.
Second, if at all possible when your baby is born, have all newborn procedures delayed for at least the first hour, and just hold your baby skin-to-skin. This is normal in birth, and what typically happens in home-births and in birth-center births; it is not what typically happens in hospitals, so you will have to be proactive. *This week* go to the hospital where you are planning on giving birth (or the next regularly scheduled L&D tour), and ask them about their postpartum practices. Many hospitals will have the following routine: after the baby is born, she will be briefly placed on or shown to you, and then taken across the room for the newborn assessment (weighing, measuring, eye goop, Hepatitis B shot [why they give a shot against a sexually transmitted disease to a newborn is beyond me!], etc.); then she will be returned for you, firmly swaddled like a baby burrito, for you to hold for a few minutes. Then, you will be likely taken to another room for recovery, and your baby will be taken to the nursery for her first bath, and then placed under a warmer (I always think of the heat lamps that keep french fries warm in a fast food joint) for a few hours, then finally returned to you, just in time for her to fall asleep.
It doesn't have to be that way. In fact, the above typical procedures undermine successful breastfeeding. When a baby is born, she has your smell from the amniotic fluid, and wants that smell; she has the ability, if placed naked on your stomach, to get herself to the breast and latch on, although mothers usually grab their babies and snuggle them as soon as they're born, unless they're prevented from doing so. If you were allowed to hold your baby skin-to-skin (with a blanket over you both, to prevent either of you from getting too cold), the baby will nuzzle your breast and self-attach within the first hour [although if you have an epidural, the baby may not have the same motor skills as an undrugged baby]. This will get breastfeeding off on the right foot.
It is certainly possible for you to have success in breastfeeding even if you don't get a great start; but this will be a great leap forward, if you can get this. But since you never know how labor and birth are going to proceed, and you don't know for sure how the postpartum time will be, get the book Breastfeeding with Comfort and Joy, so you can get the best help, even if breastfeeding gets off to a rocky start.
Oh, and I never needed any breastfeeding paraphernalia, but everybody's different.