Superuser and blackopps both make great points here. I think before trying to go out on your own you should try working for one of the local limo companies in your area for a year or two. You can develop some relationships there and network out of it when you're ready to start off on your own, it also helps you learn about the business and how to charge clients correctly, how to get farm-in, how to service properly, and how to learn the city in ways you didn't know before which will all come in handy for you as a professional chauffeur.
I've been on uberblack/uberSUV for about 3 years now and I find that the less I have to rely on it for every day business the better off I am. The expenses are high, even if you office from home. You will need $3,000-$4000 per year just for commercial insurance on one vehicle, another $1000 per year just for permits and parking tags, $120 per year for wheel chair access extortion by yellow cab, client/reservation management software which can cost you around $80/month, legal fees for running your company can range anywhere from $200 per year to $1000 unless you plan on doing it yourself, then there is gas/tolls/oil change/maintenance etc for your $50+ thousand dollar vehicle.
Realistically, you need to be averaging around $300 per day in gross fares for it to be worth it. You won't get that from uber black/SUV, even if you work the right areas you will only average around $200 or less per day on the ridesharing service, and after expenses and taxes you're better off working for a transportation company at that wage than starting your own business, sadly.
I run with one big corporate client who gives me about 70% of my total business and I usually work the hotels or uber or farm-in for the rest of it. Doing it this way you can succeed and make some good money, maybe 60k-90k per year with one car is the max. But, you will be working 7 days a week and you will be working at both sides of the clock during the busy seasons.
Best of luck to you, hope this helps.