Working with metallic threads can be very frustrating and make the process slow, but the result can be very rewarding!
I've experimented with some methods to make the stitching process easier. The best I've found so far is to glue the ends. I use to do it with white glue, but then I used the glue gun, which is faster because you don't have to wait until the glue is dry.
The trick is to use only a tiny dab, and then flatten it with the fingers (or else it will ruin the fabric), using two threads it's best if both ends are glued at the same time.
The good thing about it is that the thread won't unravel, and it tangles less, so it is easier to stitch the motif. I've only used it with DMC, but works on metallic, jewel effects and pearlescent effects.
But to make it run better through the fabric, mixing one strand of the metallic and another one of the same color (non metallic), will keep the thread from tangling.