The space you select should provide enough room for all of your equipment, but if it doesn't then you'll have to decide where to set up the equipment that the space could not accomodate so it's still convenient.  You might want to designated areas to certain tasks, this does make the work process easier.  Your desk must fit into the room to allow for full access to drawers and surface area, yet still provide space to move around and for other equipment.  Large desks in small rooms does not always work well, you still have other equipment and supplies that must share the work space.  A space that's too cramped with little or no desk space can make work difficult and limits the amount of equipment and supplies you might be able to access.

Your space needs to provide comfort and motivation.  It should be cheerful and feel personalized, as if it were a little piece of territory that is entirely your own.  If you've ever visited a business that provides it's employees with cubicles, you've probably witnessed some of the most bizarre decorating known to man.  Decorate using images and colors that will motivate you, and objects that you can focus on to spur creativity and imagination.  Make it a fun place to be, the endless hours spent there will be more of a recreation than an occupation.