A large percentage of your clients belong to a Group, Club, or Association. These groups gather together on a regular basis and many have guest speakers.
As part of your business practice it should be standard procedure when securing a client that you ask if they belong to a Group, Club, or Association.
Implement a Club of the Month drawing and the lucky club that is drawn would win a lunch sponsored by your firm.
Another approach is to ask if their Group hosts guest speakers. Offer to be that guest speaker and exchange for 30 minutes of their time you will provide lunch.
This is a very high impact, low-cost marketing approach.