There are so many artists I admire that are incredibly skilled at drawing from imagination. They may or may not have some secret method for achieving this, but I personally haven't cracked their code. The reason I don't draw from imagination is because I don't know how.
Instead, this is what I strive towards.
Mastering the skill of drawing from MEMORY.
When I draw something that doesn't exist, I am using a combination of these
3 methods for faking the skill of drawing from imagination:

  1. Drawing from observation. I typically start with a reference image, which I use as a starting point and I alter or exaggerate it to fit my needs. 

   2. Drawing from memory. I rely on my memory of all the things I have drawn and painted in the past to tell me where the shadows should be on a given shape, or even the makeup or anatomy of an object I have drawn from a reference before, like a cat or an apple or a cloud. I remember painting or drawing it and I take what I learned about rendering that object and apply it to the current project.

  3.  Draw and redraw the idea. I try to push it further each time until I achieve the look I wanted, or until we've both just had enough and I have to move on.

 Playing with the image from memory in preparation for an oil painting. I like the second cat lurking below in the first drawing, so I think I'll add that in the final version. :)


So basically, there isn't any magic trick to drawing from imagination that I am aware of, just practicing and doing the best you can with the experience you have is the method I have always used. 

For some tips on getting there, here is a video from a great teacher I know who shares his own methods and struggles with this topic. 

Kris and I have shared work space for our entire art careers. Many of you have visited our galleries and hung out with us in the areas where we created art daily. These spaces have evolved with us as our work needs and available space have shifted over time.
Let's take a little tour, shall we?
I must admit that my own studio space was never even close to this neat before I married Kris. He is excellent at organizing and he made sure my art supplies all had a place to call home. It has worked out well for me to learn from him how to put my toys away at the end of the day, especially since we've had our studios in public spaces a lot of the time. Right now our space is private, but old habits die hard so after 15 years we still work pretty clean.