ok, I'll start. I brew coffee and mix in a few T of sugar until the sugar dissolves. I add enough coffee to 5 heeping T of henna to make a toothpaste consistancey.
I let this sit for 3 hours or overnight. I then add 2 T lemon juice and 15 drops cajeput oil and let sit another 2+ hours. this gets a pretty dark stain.

Hi, here is my recipe.
20 grams or 1/4 cup body art quality Jamila henna
1 1/2 teaspoons henna
1.5 ml or one teaspoonn cajeput essential oil or lavendar oil
1/4 cup lemon juice
extra lemon juice

mix henna with 1/4 cup lemon juice and cover and let sit in a wa rm spot for 8 hours or so
add sugar, oils, and more lemon juice to desired consistency and let sit covered another 8 hours or so in warm spot.
The recipe is what we use everytime, with Jamila exclusively.
JAmila takes longer for dye release and other hennas may take a shorter time period.
This is our guarenteed recipe for jamila , it works for us 100% of the time.
I also like the KISS method-keep it simple stupid-as it makes less variables to ruin the henna experience.
Flavia