What skills should business analysts acquire to add value on a project?

One way for a business analyst to really add value on a project for a customer is when he/she understands the customer, industry and competition well enough to be able to give valuable solutions and suggestions. Analysts, in most of the projects that I have worked on, do not specialize in a specific domain. They start on a project with very little knowledge of the customer’s business and slowly learn the domain as they go. They are mostly taking requirements from the customer and managing scope. What should the analysts learn in order to really make a difference to the customer (and also remain in business ☺) and how should they go about doing this?