Loveable37- Someone else could probably explain it better but the basics are to get henna that is Body Art Quality which is the safest one to use. Always do a strand test first with hair gathered from a comb or brush to make sure it doesn't disenegrate, weaken or turn the hair funky colored! When it comes to mixing, everyone does it different, but everyone need henna, a terp. to release the dye ( lemon juice or apple cider vinegar), and warm water. Alot of ladies also use different oils, honey, herbs, and/ or conditioner to help make the henna more conditioning rather than drying like it can be when used alone.
Personally I really like Lush brand henna from the Lush store, although it's not for body art, it doesn't have metallic salts or compounds which cause serious trouble with the hair. I use it in Noir and it makes my off black hair darker and stronger, but I am yet to see how it reacts with my relaxer, so I'm going to do a strand test with before using relaxer all over my head. So I love it right now, but am not positive I'd reccomend it until I get relaxed in a month or so.
HoneyDew- Once again thank you for the info! You henna guru, you!