Of course! When choosing reference images, look for smaller amounts of colors and sharper shadows. Open the image along side your art studio and trace out objects in one color, then outline shadows in a different color. Use a large enough canvas, but not too large--palette size and canvas size grow proportionally when drawing fine details, find a balance and keep them small enough to be manageable. Dithering helps with softer shadow transitions. Once you complete the piece, try different color palettes (of the same size). Sometimes the original colors appear flat when they're simplified; altering the palette can renew some energy. Sorry for the essay, hope this helps 

Thanks @roommat381212! The original reference image had a portion of the Earth to the astronaut's left, resulting in some inconsistencies when I decided not to include Earth in the final version. It took a long time to condense the reflection to just 16 colors, but I'm proud of the result.