The designer's (or organization's) philosophy and management perspective may dictate a specific approach. Some approaches guide the overall goal of the design while other approaches guide the tendencies of the designer. Typically, a combination of approaches may be used if they don't conflict.
In a large perspective, Dino Dini (see Dino Dini at wikipedia.org [1]) suggests that design can be defined as "the management of constraints" and he identifies two kinds of constraints, negotiable and non-negotiable. Taking this view, the first step in the design is the identification, classification, and selection of constraints. Design then proceeds from here by manipulating design variables so as to satisfy the non-negotiable constraints and optimizing those which are negotiable. It is possible for a set of non-negotiable constraints to be in conflict resulting in a design with no solution; in this case, the non-negotiable constraints must be revised. Some common approaches that address the management of constraints include:
Assuming one takes a more structured path to design (i.e., not the seat-of-the-pants approach), design Methods, the actual steps one might take, typically include:
The old phrase of "Well, back to the old drawing board" teaches us that designs can fail and redesign is often necessary. Something that is redesigned requires a different process than something that is designed for the first time. A redesign often includes an evaluation of the existent design and the discovery of redesign needs. These findings often drive the redesign process.