First of all - welcome to lawnsite. Lots of very intelligent people post here that can be of tremendous help to you (and me and all others). The people that post here really have a desire to assist others and expect little in return except feedback. It's a great bunch here......
The business side of landscaping is the same as the business side of any service business. Cost of good sold plus depreciation, plus G&A subtracted from income leaves you profit. I tell people that if you just want to cut grass and be outside, you won't need much of a business plan. You can make a living that way..... However, if you want to manage a business, then treat it like a business.
Best reading material you can find (in my opinion) would be:
Nickels, McHugh, McHugh
Can be bought at Barnes & Noble (in store or on-line).
Read it cover to cover and operate it as a business, and you should do fine (assuming you know the technical aspects of landscaping - which I am not in any way minimizing with this post.... because that too is VERY important as this is like every business and has its own "science").
This business has made people millionaires and it is due to hard work and good business ethics. Good luck and welcome to the club....