If you can figure it out... PLEASE LET ME KNOW!!! My teeth were not very white to begin with, and stain very easily (avid soda drinker; no coffee or tea). I was told that braces can sometimes make teeth appear more yellow than they are because the light that shines through the tooth is diminished (especially if you have metal brackets).
I asked my ortho if I could use a toothpaste with baking soda and peroxide in it to help diminish the surface staining. He said it would be okay, since the ingredients in those types of toothpastes aren't high enough in concentration to actually penetrate the tooth (like whitestrips, gel, etc.) I can attest to the fact that he's right. I used that toothpaste at least twice a day for 3 months until I changed my metal brackets to ceramic, and after he removed the old ones, I got to rinse my mouth at the sink and took a good, long look at my teeth. There was absolutely NO difference in the are where the brackets covered vs. the surrounding area.
I don't think switching from coffee to tea will make much difference. Both stain just as bad, I think. I'm trying to drink "clear" sodas, but... I need my CAFFEINE!!
So, you may want to try one of those toothpastes. Other than that, I can't think of anything. I hope you get lots of responses here!!
-Cathy