Not the very best picture, but you get the idea.
I tried the satin stitch without doing the outline, and it looked horrible. So I am doing the outline, then the satin stitch. I'm using 2 threads, going through the holes plus once in between the holes (so it's sorta like as if I'm working on 36 count instead of 18, if that makes sense). Sometimes it's a little difficult to pierce right in between the holes, but the 2 threads seem to fill the space nicely anyway, so I don't think it matters much.