Welcome to PT!!! I also believe in adopting from shelters or rescue groups. Can you tell us more about your soon to be kitten?
You can start getting kitten supplies:
1)litter box
2)clay litter- better for kittens because kittens tend to eat litter
3)scratching post
4)cat bed or you can use a small box with a towel in it
5)cat toys
6)kitten food
7)dishes- I like to use stainless steel because they're easier to clean and can help keep cats from getting acne

You may want to adopt 2 kittens so that they'll have a companion and a playmate.