Here is a great way to make sure your facings lay nice and flat. After you sew the facing and clip your curves, press the seam allowance towards the facing. Then stitch on the seam allowance, as close to the seam as you can get. This will anchor the seam allowance to the facing, and create a nice, crisp edge when you fold the facing inside the garment. And it also helps to keep it from rolling out!
By the way, I'm looking for any advice about sergers. I might break down and get one some time this year, but they scare me half to death. Do you have one? Do you like it, and is it easy? I mean, really, really easy?