My daughter and I make ALOT of tea dyed hangtags. We make pretty hangtags out of them for gifts. We also use these for all our price tags at the sale.
I actually don't use tea - I use coffee. Instant coffee. It works much faster.
I just pour some coffee into a pan of water. Let the tags soak for a few minutes. Longer if you want them darker. Put them on a cookie sheet. Put them in the oven on very low heat - just enough to dry them out quickly.
Check them every few minutes. Once they are dried (they will start to curl up) I pull them out, let them cool and bag them up.
My daughter and will stamp them and glitter them for pretty tags for gifts.