Don't learn in black

I just learned the excellent mattress stitch (q.G.). However, I learned it using black yarn to unite black motifs. Don't do this. Make a few motifs in a light color and use a medium or dark color for the joining. Really. The stitch worked great for me, but as I made them, the stitches disappeared instantly into the deep-space-like darkness of the motifs. So when I had to undo a stitch or so, I had to peer at it using bright light. Learning anything with a dark yarn is a bad idea because you can't see the 3-D effects of shadows.