Update: I think I've finally decided on a henna/amla mixture, based on strand tests I've done in the past 1.5 weeks. Will do henna the day after Xmas. I'm using Raj Twilight.
I'm aiming for some sort of warm red with burgundy tones mixed in. The henna might not even show on some of my darker areas, but the gray areas could make this ... interesting. Too much brassiness or too much burgundy could spell trouble since my skin tone is yellow and kind of olive. I'm not totally confident about pulling this off, but I'm feeling adventurous
I've created a new album called "Pre-henna" if you want to check out pics of how my hair is looking now, before I take the plunge - my layers are longer than in the other album. I'll add post-henna pics after hennaing too, even if the color is disastrous. If disastrous, I'll trouble-shoot to correct the color, then post those pics