I've been doing enemy graphics quite differently lately. My latest method:

Draw it in Photoshop, resize it and reduce the color count to 16 in GraphicsGale. It's quite easy, so enemy graphics shouldn't take forever now. Plus, I can keep the high-quality versions and use them later to make a nice-looking out-of-game Bestiary!
Also, this is the boss of Viridia chapter 3. It's not very menacing at all, is it?