Take a hair loop or crochet hook and thread a micro ring onto it (photo 1). Then take about 5/10 tinsel strands, hook the hook of the crochet needle onto the tinsel (or pass the tinsel through the hair loop). Now pull the tinsel through the micro ring and make sure the length of the tinsel on both sides of the micro ring is about equal. Tie two good knots in the tinsel (photo 3). The tinsel is now ready to be placed in the hair. 

Now slide the micro ring that is attached to the tinsel onto the hair loop or crochet needle and grab a strand of hair. Slide the micro ring onto the hair strand, slide it about 1 cm towards the scalp, and pinch it tight with pliers (photo 4). 

Now add another loose micro ring to your hair loop and crochet needle and grab the same strand of hair where you just attached the tinsel, including the tinsel strands. Slide the micro ring onto this strand and slide the micro ring upwards until it can't go further and pinch it tight. You will now see two micro rings stacked on top of each other (photo 5 and 6).

Now the tinsel hangs nicely straight down and is securely attached. :)

You can also choose not to place the second micro ring underneath, but that’s up to you. The advantage of the second micro ring is that, IF your knot isn't tied properly, the tinsel will still stay nicely in the hair. If you don't place the second micro ring, the knot might come undone and you could lose the tinsel.