I tried to put a little water in my hair to massage it evenly in the same manner the box mixes suggest. That was really messy and the entire sink was covered with gritty brown goo (henna will flake into grit when it's dry). Keep rinsing the hair, and sink, until everything is clean. Be sure to wipe off your ears and neck.
Looking at this Medusa-style do I came to the realization that although several sites advised not to use shampoo or conditioner it was necessary. My hair was a huge heavy knot otherwise. And it still smelled strongly of hay. So I used the conditioner that comes with the box mixes. It was a very pleasant coconut. As soon as I applied the conditioner my hair immediately went "Ahhh!" and relaxed. I re-wrapped it in a clean towel and kept in on for about 10 minutes. I would have kept it on longer but truthfully I couldn't wait to see my new look.
Now to be nit-picky I can tell the hair along the sides of my face and temple aren't as colored as the rest. Whether this is from getting a little grapeseed oil on it when I put it along my hairline I'm not sure. The good thing about henna is the frequency in which it can be used. I might make up a very small batch tonight with water to do a little touch-up tomorrow. From everyone else's testimonials it'll blend in with what I did last night.
I'm not claiming to be an expert but I'm confident I'll be using henna from this point forward despite the time and mess. But then again, that's what happens when your dye-ing to be red.