Go fill up the gas tank in your truck and your mower, and see how long it goes. If it lasts a week then divide the cost of the gas by 7 (number of days in a week). Then you know how much your daily gas costs are. Do this with every other expense, (payroll, parts, equip. maintainance, etc) and you will come up with your daily expenses. Then take your daily expenses and divide them by the number of hours you work everyday and you will have your hourly expenses. Then you will know that you need to be making AT LEAST that numer to break even. After that is done, figure out how much profit you want to make per hour, and tack that on and you have your final hourly price.
After you get your hourly price, then you can go give out estimates BUT do NOT tell potential customers your hourly rate, tell them what you would charge to do the job. If they find out that you are charging $40 per hour (or however much you are charging) they won't want to pay that!
As far as residential & commercial stuff, yes usually you do charge more for commercial accounts. The reason for this is because most commercial accounts require that you have insurance which makes your costs go up.
The Institute for Incomplete Studies found that 3 out of 4