Show your client on paper what has been working and what hasn't. Convince him that the services will give him the competitive edge he needs and turn his website into a high octane selling machine. Convey to clients you have the expertise to fix whatever is broken...
Should you, as a consultant, can deliver on those promises, then you can expect to acquire a strong client list along with a good reputation. Your clients benefit and you also become the next amazing Internet Marketing Guru.