There are two sides to the process of designing a home - aesthetic and functional. Even if "form follows function", design preferences play a key role in managing the expectations of the customer. Some people are drawn to the work of a designer because the aesthetics appeal to their taste, while others prefer designs and styles they are familiar with. In all cases, good design is a function of understanding, what the customer likes, what they need and, what they can afford.
Photos and scrap books are a great way to collect design ideas. During the early stages of the design process, try not to think too literally. Use your ideas to inspire the designer. Show the designer what you like without telling him or her what you want. You may be surprised what a little thinking outside of the box will achieve. Allow the designer to express their interpretation of your requests. They may have ideas and solutions that you hadn't considered.
The personality types of both the designer and owner, play roles in the design process. There's a big difference between practical and flamboyant. Accountants, athletes, teachers, entertainers and CEO's may have completely different agendas. A responsible designer should know which types of owners he can please and refer others to another designer.