I would start by introducing myself, explaining the services that I offer, and let them know the benefits of the service that I am providing. I would also let them know that even though maybe at that moment they are not in need of the services that are being offered, please keep me in mind in the future. And then I would always follow up with them if I didn't hear back from them, maybe every couple of months, two or three times every two to three months, just to check in with them and to see if my services would be needed.