Just an easy one but when I first started one of my little old lady customers was complaining to me bout a plumber that charged her $70 to come and change a tap washer....From that day on I carry a stash of washers in my glove box and have let it be known to all that I can help em out in that way.
Something else I'm going to try when the cooler months approch is carrying a roll of fly screen wire and any house I see with damaged ones I'll offer to repair. Quick easy and a bit extra on the job.