Keep it in mind that you need to do research after research. There are many things you can forget so make a list.
Here is a list to start you:
20+ gallon long tank with secure screen lid(use lid clips)
Atleast 2 hides
waterdish
Aspen substrate
decor plants..etc
Heat pad (made for the size of tank)
Digital thermometer with probe
Digital thermostat to control heat pad or a cheap dimmer to get you by.
(Humidity hide can be avaiable during shed periods. A plastic container with moist moss and a hole to get in it)
Babies can be housed in 10-20gallon tanks. Adults need a 20L or bigger, I suggest bigger. Keep snakes seperate.
There is a warm side and cool side. The warm side needs to be around 82-86degrees. 90degrees is the risk spot. Cool side is room temp.
I suggest starting out with a 20L or bigger, just to save money. Remember when you choose your snake to ask about it. When you bring it home leave it in his/her tank for a 1 week without handling or feeding. Always feed F/T (frozen/thawed mice) You can feed a few different ways. You can do every 5 days, 6 days or 7days. I suggest 5 days to start up a baby cornsnake.
I suggest feeding in a seperate feeding tub. A feeding tub is basically a plastic bin with lid, shoe box with lid, or something that closes and you can secure it. Feeding tubs have benefits. They allow you to put your snake in something empty to feed without swallowing substrate, it also allows you to spot or fully clean the tank.
Any questions? Keep asking!
Here is my setup to give you an idea,
http://www.cornsnakes.com/forums/album.php?albumid=1046&pictureid=7721
My Okeetee cornsnake's name is Tang and that is a 20 Long tank. I have a 40 Long waiting for him. Coolside is to the right and warm side to the left.