Sometimes it is difficult to look at a deck plan on paper and understand exactly how it will look and feel in real space.  You may need to layout the design to actual scale at the location to be able to get comfortable with its form and proportion.  Use a tape measurer and a garden hose or some spray paint to express the designs outline.  This space will be the footprint of your deck. 

Stand within this area and try to get acquainted with its size and shape. Does it feel larger or smaller than you anticipated?  You may want to arrange some furniture within the outline to help you visualize how the space will be used.  Will you have enough space to move around the deck freely or will it be too cramped? You may need to make some changes to the plan in order to adjust to your findings.  Can you visualize what the deck will look like up in the air?  Try to picture where the posts will be set and how the stairs will approach the ground. Your deck may start to seem very real all of a sudden.  Hopefully you are pleased with your design thus far and all the hard work that has gone into it.  If you still are unsure about the general design you may need to go back to the drawing board.