In his book, "Keys to Drawing with Imagination," Bert Dodson suggests that by creating a series you can more fully explore an idea than if you did just one drawing of a subject. He says "a workable theme has two qualities: 1) It must arouse your interest enough to carry you through a series of drawings; 2) It should have defined boundaries."
"A theme gives you sustained focus. You can create a limited series of maybe a dozen drawings in quick succession. Or a theme can take years, or even a lifetime. Once you've chosen a theme, give it a title, being specific. Example: if you like to draw your cat, by titling a series The Many Poses of a Sleeping Cat you have given your project a particular shape. Simply draw the things that interest you. The artist chooses and executes the theme. The theme inspires and energizes the artist."
He suggests "do a dozen drawings on a single theme; make them relate visually as well as conceptually...create a unified look to this work, so that if you displayed the pictures, they would appear to belong together. Choose a theme that you can generate some passion about--something that will hold your interest over time. Try combining different subjects (masks, circus, etc.) with different kinds of approaches and methods (puzzle pieces, mirror images, etc.). As you work , display the drawings and leave them up a while. You can learn a lot by studying your work over time."
I have a series that I started several years ago: Terra-Cotta Faces. I am currently working on a drawing in the series of a terra-cotta lion head "mask" that was once one of twelve that were on all four sides at the top of a bank building here in Montgomery. In the late 1800s and early 1900s builders began to use terra-cotta for the ornamentation pieces that were to go anywhere above the first floor of a structure. The real material (granite, marble, etc.) could be used at the first floor and the lighter weight terra-cotta was used for everything else and could be painted to look like marble or granite or what ever was used. I will post the drawing once I have completed it.
So, think about doing a series. It can be fun to come up with different ways of drawing the same subject over and over. Use your imagination!