I'm going into my first year as well this Spring. From what I've learned just use your hourly rate of $50-60 + material costs for all your mulch jobs. You'll be able to get a feel for how long it takes you to do certain jobs after you get some experience. At $60 per hour with low overhead you are going to be making some money. It's hard to truly know what to charge and what you're worth until you get a year under your belt. Keep track of all gas, oil, repairs, etc. throughout the year and figure out your true costs next year at this time. Never mow a lawn for under 25 I don't care how small it is. You have to figure that between driving there, unloading, trim, cut, blow, and load back up it'll be at least a half hour. Then you add in equip costs, overhead, gas for truck/equip, insurance, etc. If you charge somebody under 25 you aren't making ****!
The best thing is when you land 3 or 4 houses side by side and you can fly through it and make a killing per hour.