If you HAVE to buy thread - I use a grey or beige neutral. BUT if you are doing a scrap, or one that has lots of colors and it's hard to identify a specific color - it's a great chance to use ANY color that would suit. Use one color on top and another in the bobbin. I prefer to sew with a slightly smaller stitch - 2.0 on my Pfaff, so unless I actually force the seam open to see the threads, I can use almost any color. Great way to use up ends of spools - and buy new thread. My favorites are Aurifil 50 wt. Superior Threads So Fine and Masterpiece by Alex Anderson.