This is an interesting article on the high level design process used by IDEO, do design all things including services, not only products:
Practically speaking, the approach isn’t complicated. In stages, it goes like this: firstly, immersion, whereby the designers research the problem by plunging themselves into it – talking to the people they’re trying to help, working with them, interviewing experts. Secondly, synthesis – whereby they gather together their findings and look for patterns. Third, ideation – brainstorming solutions to the real problems identified by stage two. Then comes prototyping, making mock-ups of solutions to try out against the problem. After that comes the product. Only at the end, at the prototyping stage, are judgments made; until then, all ideas are given equal weight.