I started by calling every single lawn care outfit in the yellow pages and having them come and give me an estimate on my own yard.
Then I measured out my yard and went to town on other peoples yards using similar estimates for similar size yards.
I don't think there is some formula where we can tell you everything you need to know to make money on every single job. You'll have to learn most of it by trial and error just like we did.
The LORD is my shepherd, I shall not be in want. He makes me lie down in GREEN PASTURES