Satin stitching can be difficult to get to look even and smooth. A few things that you can do to fix those problems are:
1. Make samples for every different combination you are doing. I don't think you have to do for each fabric if you are making a quilt, unless you've got a fabric that is a different fiber content. I do think you should do a sample for every thread, not just every type of thread. I haven't always done this, and I've always been sorry.
2. Stablize. I prefer Pellon mid- or heavyweight tearaway stabilizer. I do not like Sulky Totally Stable. You may need more than 1 layer of stabilizer.
3. Thread tension to prevent bobbin thread show-thru. I turn my tension to 3/4 (just lower than 1) on my Bernina 1001 when using the metallic and holigraphic threads. On my Bernina Artista 180, I have to turn the tension to zero (0) and use the embroidery bobbin.
4. Lubricant to prevent breakage. I use Tri-Flow Superior Lubricant with Teflon. "Draw" a line vertically along the metallic thread. Use as little as possible.
5. You want to use the smallest needle (to prevent bobbin thread show-thru) with the biggest eye (to prevent thread breakage). There are metallica needles available that are coated to help prevent shredding of metallic thread.
6. Look at your stitches from at least a foot (30 cm) away. A lot of the imperfections will disappear with a little distance, and unless your item is being judged for perfect workmanship, it's not going to matter that the satin stitching isn't quite perfect.