There are quite a few design and development methodologies to work with. Each has its uses. We primarily focus on three.

With the waterfall method, the project is divided into smaller processes, each of which has a start and a finish. Progress comes through starting and completing each phase before moving onto the next. Typical steps in this method are:
Each phase could be, and typically would be, entrusted to a different member or team.

Specific agile methods, like "pair programming", form part of this later methodology. It uses some of the same processes as the waterfall, but as the word agile suggests, one phase does not require a phase prior to be complete. Thus when changes occur, they can be made simultaneously in more than one process. This can increase productivity. Tasks are broken down into small increments with minimal planning. Iterations through the complete process (analysis, design, coding, testing, and acceptance) help reduce problem areas.

RAD (Rapid Application Development)
This type of methodology uses minimal planning in favor of prototyping. A lot of demonstration projects are built this way. For very small projects this could be ideal since time is used mostly for design/coding. Delivery from start to finish is hastened—and a result can be tested much quicker.