This is how you get really smooth, lovely satin stitches. Outline in split or chain stitch, fill in the area with chain or long & short stitches, and then do the satin stitch. The underlying stitches support the satin stitch and help it to lay smoothly.
Mexican Embroidery Patterns: Embroider Your Own Peasant Blouses
Here's the completed piece, based on the free embroidery pattern above. If you look carefully, you can see where the "stem" and "back" stitches have been used to create a textured, three-dimensional effect.