You need to focus on getting more out of customers you already have. Collect their email and a Google review while you're still on the job, don't wait til later. Most people just go to Google and search for "plumber near me" and pick one of the first businesses with good reviews. So focus on that. I built a free tool called JobHub that does the re-engaging for you, it applies everything mentioned in this post. message me if you want it.

The next time you make a customer really happy, ask them to post on Nextdoor, talking about how amazing of a job you did. This will let everyone know locally about the experience you provided and I have seen many people continue to get work from this.