I've never dyed my hair.  I started getting grays fairly early in my 20s and now it's getting to be more than I like.  I really don't want to use chemicals.  Besides the health/carcinogen concern, I know I wouldn't keep up with it enough and would wind up with the line of gray roots that my mother promptly dyes over on her own hair. 

I don't mind some gray.  That's why I've put up with it for so long.  But I have very dark brown hair and the grays are standing out a lot lately.

My aunt uses henna, but she has darker (almost black) hair and her dye job reminds me of when my friend used red kool-aid as dye in high school--it looks completely unnatural. 

I don't want to change my hair color (at least not drastically)  I just want to blend the grays a little better--you know, make the grays look like highlights instead of grays.

I was thinking about using the coffee method, which seems to have a simplicity that's more my speed.  But now my question is, does any old coffee work?  For example, is instant the same or is instant technically some sort of chemical fake-coffee?  See, I don't have a percolator, but if instant won't work, I'll totally attempt any alternative brewing suggestions. (would making a makeshift teabag with coffee grinds work?)  Do different coffees have different shades?

Anyway, looking for help!  Thanks a bunch for any advice you can give.

Welcome!  You can also check out the Mehandi.com site.  The amla added to the henna and indigo will in fact give you a cooler brown tone.
I myself haven't tried the coffee method.  For great information you can check out the two sites.
HTH

Thanks for the input.  Just trying to get ideas.  I still don't know if/what I'll wind up doing.  This is a big help though.