I'm goona pitch in here!
I'm a student and I have a good business. This summer I had about 40 clients for a while and I was working 7 days a week to keep up with the extra work like weeding and other odd stuff. All in all, I made a pretty good profit I must say. Enough to pay bills, tuition, LOTS of commercial equipment, truck repairs, summer tires, going out with the GF and the list goes on... What I learned is that I had good prices, but I can go a little hire. I would charge about 20-25$ per lawn cut and sometimes 45 for the big ones that took me about 1.5 hours. I got lucky on one street where people kept coming and talking to me. Why? Because I look like a Pro with all my equipment, great service and respect. Turns out in that area, alone, I can do 5 lawns (trim, mow and blow). To me, that is real good. When I am with someone, I can do this in about 50 minutes wich is even better. I had good prices and got rid of the competition, because the profit goes up when I stay in one section I do a big load.
All I can say is adjust your prices to what you need to pay. Most big shot guys that look at me on the roads charge something like 35$ a shot or more, but that is because they have three monkeys jumping on ZTR's hacking with trimmers and blowing there heads off. Not very awsome. I'm in the middle of all of this. Better than some kid that just mows and a little lower than the big shots.
I must state that I started with my dad's mower and no blower :O. I would only do 5 yards a year and be excited with that. Now, I am here with a bunch of commercial equipment taking over the garage here and there and a part of the back yard (vintage lawn boys). Over the years I have learned a lot. What clients really like is that you come EVERY week or two regularly. If you come when you want they hate that! Come like if you had to go to Church each Sunday. Also, start with what you have. Once you get money, get better stuff. Not necessarily the big ZTR. Just maybe a wider mower, better string trimmer or whatever. Also keep a book of all your client's name, phone number, e-mail and write down EACH time you mow the lawn to keep control.