I went by the instructions that came with the cassia which said to mix it with warm water and let it sit for 15 minutes before applying. I didn't add anything else to it -- some of the people on the 4a thread use green tea rather than plain water (which I will do if I try it again) and adding things like honey or a little bit of oil, but I wanted to try it "plain" first. And although the instructions say to leave it on for a half hour, I left it on for about two hours based on what I read on the 4a thread. If I had started earlier in the morning, I would have left it on longer. I really did enjoy the experience and am debating trying it again. If it were something I didn't have to order online, I definitely would keep up with it. Lately, I prefer to keep everything simple and use only products I can obtain locally.
For a while last year, I also went back to using cones but quickly abandoned them again. I really didn't like the feeling of them in my hair after being cone-free for so long, and they also did a real number on my scalp which took a few months to clear up. But a lot of people can use them with no problems, so I say whatever works for you, go for it!