Litter pan and Litter - make sure the litter pan is an appropriate size for your new kitten, if it is to high sided, you kitten might have trouble climbing in.  Also, it is usually best to use non-clumping litter for young kittens as they tend to "taste" things, much as a human baby does. 
Clumping litter can cause intestinal blockages if enough is digested.  You can switch to clumping litter if you like when your kitty is older.

Food & Water - ask your breeder what type of food your kitten is used to.  Have a supply on hand.  Often breeders will send you home with enough food for the first few days.  Don't panic if your new kitty is hesitant about eating at first.  Remember, the kitten's surroundings have just changed.  He/she may need a day or so to adjust.  However, if your kitten doesn't appear to be drinking keep a close eye out.  Dehydration can be dangerous and set it fast.  Make sure fresh water is always available.  If you are not sure your kitten is drinking/eating, check your litter box to see if it has been used.  It is possible the kitten is eating or drinking when you are not looking.
As always, if your kitten doesn't appear healthy or "seem right" to you, call your vet or breeder for advice.

A Bed -  your new kitty needs a place to sleep.   It need not be fancy, but should be comfortable, warm and dry, clean and in a safe place.  An old soft blanket can do the trick nicely as can a store bought bed.

Toys - Ever walked through the toy section at your local pet supply center?  There are tons of options here.  But you need not go broke buying toys.  Some simple suggestions are...a ping pong ball, small rubber ball, a small rolled up piece of paper.  Beware of dangerous items such as bread ties (when swallowed they can perforate an intestine), tinsel from a Christmas tree, sharp edged small objects and dangling electrical cords.

Grooming Items - Ask your breeder what they recommend.  For a long haired kitten, a comb or brush will be a must!  Your breeder should be able to advise you on what type.  I prefer a greyhound style comb myself, and a pin brush (the kind without the balls on the tips).