Obviously, the first thing to do is research. Find out how much it will cost you for a server of your liking. Find out how much per month it will cost to keep everything running. Then figure out a decent price to sell for and see if you will make a profit. After you figure out how to make a profit it is time to start marketing, and selling. The last part is the hardest, and you definately need to research how to market before you just jump in, otherwise you might lose your money.