two words....
LETTINGS AGENTS
Get on the books as their preferred suppliers and you will get refferals every day, im listed as preffered supplier to three of the high end agents in my area..it brings in lots of steady work, easy empty homes plus you can leave your cards, I usually get at least one extra job per ten cards left in rental properties during a tenancy
Also, have some "we were working at number XX today," cards,post them through the neighbours doors, if your good, you will hopefully get some refferal work from your customers as everyone likes a recommedation, plus they can pop round and actually see your work!