What is the best advice you have ever received, whether you figured it out through years of work or some wise soul once told you. Such as how to mow better, how to respond to customers more effectively, what equipment to buy, etc. For me, mine would be to "never say no." If a customer asks you to do something for them, no matter how much of a pain it is, I do it. If they ask me to wash their car, I will. Do what ever it takes to make the customer happy. Many times they ask me about fertilizing, which legally I can't do, but I say oh sure I can take care of that for you and I will call a place that does fertilizing and have them do it. By saying no you bring on the possiblities of being replace, at least that is my take. If the customer is happy, then I'm happy!