An ‘evergreen service’; something that many people want, need, and can afford even in tough times, is a key weapon in the service business arsenal.
They can keep you busy in between larger projects. They can provide a ‘(small) loss leader’ that can be offered to acquire new customers.
A bathroom remodeler could offer bathtub resurfacing.
A window and door contractor could offer window cleaning.
You get the point.
I also suggest using an evergreen service in marketing campaigns due to the audience.
How do you know what exactly is an evergreen service though? How do you know which services have a large audience that buy? How do you know what has juicy profit margins?
Simple, look towards franchises. Spend some time look at local advertisements from similar franchise service operations. Browse one of the many online directories for ‘franchise opportunities’? What services are they pushing? Large scale service franchises invest big dollars in market research and stick to only high profit margin services that are in demand everywhere. If they’re slinging them, you can bet there is a profitable evergreen market for them.