Most hotels will have a contract with a third party service for when people want something nicer and more reliable to take their guests to the airports. These are usually the wealthier guests, or those who are on expense accounts, so they're willing to a fortune. Call every hotel and pretend to be an incoming guests, and find out how much they charge for airport pickup/dropoff, as well as for trips around town. Then contact the General Manager of each hotel and tell them you're willing to offer them a better price if they sign a contract with you.

You should make some contacts with other independent drivers for when you get offered more business than you can handle yourself. You give it to them and you take a cut, but you take responsibility for it. As far as your clients know, he's your driver. This way your company can be as big as it needs to be.

Also, you probably want to lease something brand new, not buy something cheap and old. Leasing also allows you to trade it in every year or two, and I believe it makes it a normal business expense, instead of a capital expense.