You have to know your hourly costs to determine your hourly rates. In addition you have to know the average going rates for your area and determine your salary.
Every thing is interrelated.
Your costs are $40 hr you want to earn $20 you need to charge $60 hr.
But if your area rate is $50 hr then you have to figure a way to cut your costs $10 hr or accept a salary of $10 hr. Your prices will be too high and you won't get enough work to stay in business.
Your costs are $10 hr you want to make $20 hr so you charge $30 hr. Your losing money.
You are low balling and leaving $30 hr on the table because you are under charging.
So you need to find out the length of your seasons by the weeks.
You do 3 weeks spring clean up, 24 weeks mowing, 3 weeks fall clean up. That is 30 weeks at 40 hr per week for a total of 1200 billable hours for the season.
Now lets say you already own everything you need to do property maintenance.
You may think your only costs are for liability insurance and gas.
Liability ins $1,200 that = $1 hr cost
Gas $100 wk @ 30 wks $3000/1200 = $2.50 hr
5 years your truck will have to be replaced $35,000/1200 = $29 hr
Were at $32.50 and then you have to figure in costs to replace trailers, mowers, hand helds, maitenance, repairs, etc.
Then add your required salary and you have your total costs.