If only one machine, I'd go with a wheeled unit. Much more versatile, much cheaper to operate. Also, a tracked unit, in my opinion, need to be bought new or near-new. Many, many people never check/change the case drain filters and the hub oil, and that can become a $10,000 lesson. You can rent a tracked machine for under $200 a day on the rare occasions you need it. That being said, I own 3 wheeled units and a T-190 currently, and a tracked machine is the BEST for grading, but you must stay on dirt 99% of the time or you will eat up the tracks. I rented tracked machines as needed for several years before my business grew to the place that I could keep one busy every single day, and then I bought. Some advise about the business side:
1) No money in just pushing dirt around--anyone can rent a machine and do that.
2) No money in subcontracting for others like homebuilders, concrete companies, etc--they want to pay you wholesale prices and give you the stuff that is too difficult and costly for them to do themselves, and they take forever to pay.
3)Not much work is available working by the hour--the rates you need to charge to earn a good living, and pay the help, and pay the excavator's insurance, workman's comp, machinery expenses, truck expenses, etc, will seem to high for most people's likes.
4) Become a problem-solver, and work exclusively by bid. If you fix a client's damp basement, repair their driveway, beautify their outdoor living space, etc, then you are improving their quality of life, and that pays a whole lot better than pushing dirt around for "x" dollars an hour. Of course to do this you must be GREAT at what you do.
5) I just said you had to do exceptional work, which is for the most part very true. But in many markets, there are LOTS of firms doing great work, so you need to set yourself apart from them: return every call promptly; always do as you promise; go bid a job within 24-48 hrs of the initial contact--the early bird DOES get the worm;
6) have shiny equipment--not new, but washed up/painted up looking neat--you can't charge premium prices with a poor image. I have 10-year-old trucks and machines with lots of miles/hours that, if you weren't familiar with the various model changes, could pass as new;
7) leave the jobsite SPOTLESS; plywood lawns, don't tear them up; keep the client in the loop if things have to deviate from the plan;
8) EAT your mistakes, and correct them no matter the cost; guarantee all work always; be honest and walk away from something over your abilities;
9) learn to judge people from your initial contact, and occasionally turn down the chance to bid if your gut tells you they will be impossible to please--a select few people are;
10) NEVER "haggle down" on your bid--that will get around and you will end up dickering and working for less all the time--even if you later regret your bid (wish you had been lower), stick to it and learn from it;
11) get paid for change orders at a rate HIGHER than your normal rate, as it screws up your schedule and makes you late to the next job--so don't do it unless you get well-paid for it--usually I just tell them I don't have time for changes but would bid the additional work and come back. CHANGE ORDERS HAVE TO BE BIG MONEY TO BE WORTH THE HASSLE ASSUMING YOU ARE BUSY.
12) Throw a little something in for free, something that will make the customer's day. Many things only take 15 minutes once you are there and it always looks good on the final invoice to list something as "no charge"
13) Most jobs have something you don't factor in when bidding that slows you down. Put a bit of fluff in each bid to allow for it.
14) Advertise. Yellow pages are expensive, but a MUST. Even after many years in business with a good reputation, lots of repeat clients, and referrals, many people will find you in the yellow pages.
I could go on and on... but my main point is the equipment has to be decent, but it is a tiny part of what will make you successful. All the people skills and business stuff if WAY more important.