I would like to hire a SEO Expert

We have two business catering to the tourist sector in New York City. The first is a vacation rental business and the other is providing related tourist services to tourists who may or may not rent of our apartments. We are in need of an SEO expert with a proven track record to advise us on what the best ways to rank high and then to manage our effort. We also want someone who can vet and manage the work of SEO people working in South America and Europe, which is where the bulk of our clients come from. We understand that this will be an ongoing process, so we we are looking for the person with whom we can have a continuing productive relationship.