Lanolin, Soothies + Pads
Nursing can be extremely uncomfortable at first. These things help!
LANOLIN
If you're breastfeeding, you want to have lanolin with you day one (as in, bring it with you to the hospital -- they should have it for you there too, but just in case). The hospital gave me Lansinoh Lanolin that's safe for the baby (you don't have to remove it before breastfeeding) and I continued to use it once we were home from the hospital. Most people transition to a less intense cream later on (you need it for pumping even if you don't use it for nursing), and I highly recommend Motherlove (much better than Earth Mama Angel Baby IMO), and also safe for baby so you don't have to remove it before feeding.
SOOthies
Another nursing essential I needed day one were gel pads, which are cooling/healing pads to wear between feedings. I used Lansinoh Soothies and Ameda Hydrogel Pads -- both were good. If you have been wearing a soothie, you need to wash or rinse off before your baby nurses. I found it was easiest to keep a stack of washcloths next to the sink in the bathroom, so I would quickly run one under water and rinse off prior to nursing.
nursing bra pads
These are an absolute necessity in the early days. There's some debate about whether disposable or reusable are preferable -- I used both. My favorite disposables were Lansinoh. For the washable/reusable ones I didn't like Medela (they were a very stiff felt material) and primarily used Satsuma pads (they were thick enough to actually be absorbent, though that also means they are potentially more visible, depending on the structure of your bra). Bamboobies are pretty cute and pretty popular, and I liked them okay, though I needed something much thicker/more substantial in the early days.