Here's an interesting tip that we recently heard at a coffee for business women.
When you are leaving a cash tip for a server or wait-person, leave them a business card as well with a note on the back offering a free product or service. For example, if you're a personal trainer, you could offer a 30-minute introductory coaching session. If you sell online pet supplies, you could offer a free animal-lover gift with first purchase. Or simply offer $5 off any product or service from your online store.
What a great way to connect with new potential customers while you reward excellent service!