Twice a year, since we have been in business, I visit an older gentleman who has a rather large home. The purpose of each visit is to determine what types of maintenance will be needed and when those projects should be done. We usually spend a couple of hours going over his list and if I see something that can wait until next year or longer, I mention it. I noticed that the paint on the exterior of the home was in excellent condition but the trim was peeling and fading. So, he decided to paint the trim this time and check on the exterior paint next year. I never try to push him into a project that's not on his list because the last handyman he tried did that and well, he is now his previous handyman.
Another thing that's interesting is that most people I meet to bid on one project, will quite often say "I don't know if you are interested in this type of other work I need done or not but I need .....". In most cases I can do the other project and when I can't, I refer to someone who can. My wife and I started this business to help people and make a living for ourselves. If I'm asked to do something I can't (for whatever reason) I honestly make the best effort to find someone else for them. By doing that, I am remembered and the next time the customer needs something (even if they know I don't do it) they will call me and ask for help. And I always try to help.
The point I guess I'm trying to make here is this. Most people are reasonable. They want to be treated fairly. They appreciate help when they really need it. They want a good job at a fair price and they are usually patient with other reasonable people. So, whatever industry you are currently in, doing whatever type of work you do, treat everyone (even those few tough customers out there) with great respect for their needs, opinions and expectations, and you will excel.