First:

Take some time to think about what you want and what you need. The first step in this process is to consider some questions that an interior designer will ask regarding your project:

For whom is the space being designed?
What activities will take place there?
How long do you plan to occupy the space?
What is your time frame?
What is your budget?
Are you relocating or remodeling?
What image do you want to project?
What is the approximate square footage to be designed (for commercial projects)?
Also, be sure to consider the positive and negative aspects of the space.

Keep in mind the more information you provide, the more successful your designer will be in meeting your needs and expectations. You may want to reference other visual images (photos, postcards, corporate logos, magazine photographs) or environments that reflect your aesthetic and functional criteria.

Next:

The next step is to interview designers. Interview several designers to become familiar with differences in personality, style and business methods. Take this opportunity to acquaint the designer with your project ideas. Keep in mind you will be working closely with the designer and you will want someone that you feel will make the right choices according to your specifications and will listen to your ideas and concerns.

Questions:

Are Contracts Important?
Contracts are very important because they allow both you and the designer to define the scope of your project. A contract allows you to specify who will be responsible for what, how long the project will last and what the budget limits will be. It is in your best interest to have a signed contract before any work begins or any money is exchanged.

How Much Is This Going to Cost?
It depends on what you want. There are many variables including the size of the project (one room or whole house?), quality of products selected (custom or prefabricated cabinets?), and the timeframe in which the project needs to be completed (two weeks or two months?). Developing the budget is a partnership between the client and the designer. As the client, you should have an active role in developing the budget. If you're unsure about costs, your designer can help. Be honest with your designer about your budget. A professional designer assesses your needs and helps you determine where to spend and where to save, prioritizing expenses while creating an interior that is within your budget. Also, remember that not everything has to be completed at once. Your designer can develop a long-range plan, consult with you to establish a list of priorities and determine a time line for accomplishing your project.

Source: ASID