Make sure to get all sizes... you will be thankful when your baby gets older to find you already stocked up on 3's and 4's...
Lots and lots of diapers, all sizes! If your gonna have a baby shower youll get a lot of the neccesities but you can never have enough diapers
Diapers and gender neutral clothing. Oh and blankets, Burb rags, bibs, wipes.. just get lots of yellow and green until you know if you're having a boy or girl. :)
I would start stocking up on diapers until you find out the gender. What I did for the first few months was I bought a gift card to target every paycheck just to start saving up money to spend specifically for the baby.