Patience is key! I agree with everyone above- shorter lengths and thread conditioner if you find there to be too much snag or fraying.
Also, test different brands to find what you like.
DMC Metallic is HORRIBLE! No one likes it!
Some people hate Kreinik, others love it. Go for #4 braid for Kreinik. Try Petite Treasure Braid if you dont like Kreinik.
Take it slow and be patient and it will turn out beautiful.
When I use metallic threads I cut into 12-inch sections. If it starts to fray moisten just slightly with your fingertips or a thread conditioner. Metallic threads can kink so be patient. If the metallic thread is for just a few stitches complete all the regular thread stitching first then stitch the metallic thread and last the backstitches.