Recently I was explaining depth and variety to my performance prep students, and out came this metaphor/analogy that really turned on the light bulb for them, so I thought I would share:
A common thing a lot of dancers do, especially those new to performing (or strangers to performance technique) is the dance equivalent of doing a painting in entirely blue - and I'm not talking monochromatic (different tints and shades and variations of blue) - I'm talking about using the same tube of blue paint for the whole painting. Translated to dance: using the same exact pace and movements/movement quality throughout an entire performance. There may be a movement she/he does really well, but they do it throughout the whole piece again and again, or the movements are all done with the same exact force, same exact meter, throughout.
You don't have to have a whole arsenal of paint at your disposal to make a good painting that's interesting to look at. So yes, you love that blue, but what if you had a tube of red paint? What if instead of blue the whole time, you added some red? And then what if you mixed the blue and the red together? You get purple! That's 3 colors (and the many increments of variation found with the spectrum between blue and red when they're mixed together)!
Back to dance - let's say the blue is your favorite dance combination. And the red allows you to do that combination slower or faster, or add a new development on top of it that changes the look (purple!). What are the basic moves that make up that combination, and where you can you go with them? Level changes? Floor geometry? Different arm positions? Suddenly that all blue painting becomes a lot more interesting, and that blue looks even better because you've started to bring in other elements that help make it special.
So make some purple with your dance!