I'm still relatively new to spriting, I try to sprite a little bit of everything, unfortunately it seems I sometimes spread myself too thin, trying to do many different spriting projects at once. Most of my work is incomplete, however I often revisit different projects to work on them. There's usually one or two different projects I grind myself on, right now they are my profile portrait, and the battle sprite for said portrait.
Typically I use or splice together a base sprite to work with, slowly customizing it to fit my purposes. For example the portrait I use as my profile started out using the Gilliam portrait. I plan to move on to FC once I feel I've improved enough to take my work to that level.