There are a couple of key factors to getting a beautifully raised satin stitch from your sewing machine. The first key point is to ensure you have the correct foot attached.
The underside of the chosen foot needs to have a groove or elevation so the formed satin stitch can pass through the foot, uninhibited.
The wrong foot can lead to gaps or stutters in the satin stitch, leaving it looking uneven.
The second step needs to be a shallow zig-zag stitch that will act as an underlay for the satin stitch to cover.
This technique is called seeding and stabilises the fabric, preventing it from stretching.
The zig-zag stitch should be open and narrower than the finished chosen width of the final satin stitch.
This under stitching will be entirely covered and not be visible once the satin stitch is completed.
NOTE: If the satin stitch is quite narrow when finished, two or three rows of straight stitching will be sufficient for the underly as it still gives a foundation for the final stitching to be formed on.