The car seat blankets are so great..... They keep your baby warm while traveling without the need for a bulky coat. Defiantly need a good warm hat too. As far as clothes probably some good zip up sleepers.
my daughter was born last aug and my son is due in 2 days, I made sure to have a carseat cover, lots of onesies and lots of sleepers to put over them. I had a snowsuit with my b.girl but never used it. (waste of money) I didn't take the baby out much so the seat cover and blankets did fine when I did go. I didn't put those big bulky outfits on them because they stay wrapped in blankets anyway.. a lot of it will not be used so just get necessities..
If your baby in born in winter a snowsuit it a good idea but I found with my first that the one in size 0-3 months was way too big for a first month and when she was ready for it the winter was over. For sleeping grobags or any other sleeping bags are great. For an older baby I would recommend a cozy toes for the pram.
Snow suits, hats,car seat cover.
I live in Wisconsin so in winter it can gey really cold. So I plan to layer my baby's clothes. Im going to buy a hat, mittens and a coat. Plus cover the baby with a blanket