My wife is a customer, first as a builder, now as the manager of a country club community. She has hired tons of tradesmen and fired more than a few.
#1 on her list is "RETURN YOUR CALLS".
Nothing is more frustrating that trying to hire someone and not getting a call back. It certainly makes you wonder if this guy will actually show up on time.
That is
#2 "SHOW UP ON TIME"
#3 "Bring what you need to finish the job when you start it"
We all understand things come up and you may have to go get something but if you know you will need something, bring it.
#4 Clean up after yourself.
Don't walk away leaving a mess and don't create unnecessary hazards for other people by leaving things laying around.
She puts price way down on the list. It is more important that you can actually finish the job for the quoted price than it is the lowest quote. The low bid is always suspicious.
I understand she might not be the typical customer because she has done this for a while but in the end I believe that is really what people want, in spite of what they say.
BTW that was also what IBM strived to do ... back when they were selling service. We called it different things but the elements were the same.