is a simple and effective technique for keeping the threads in a stitch parallel (untwisted) and flat. Here's how to do it.
1. Bring your needle up through the fabric, then put it between the two threads near where the thread emerges from the fabric.
2. Put the needle into the fabric and finish the stitch. The needle will keep the strands parallel.
3. If the floss is very twisted, you can "comb" it with the needle beginning where the thread emerges from the fabric to make a gap so that the needle can be inserted between the strands easily.
4. Depending on how particular you are, you may railroad the top and bottom stitches of each cross, or just the top stitch, or just when you find that the floss is beginning to twist.