I found a fantastic site the other day dedicated to fabric dyeing. What I loved most about the information was how simple the dyeing process was laid out- IF you follow the steps and prepare, prepare, and prepare some more. I dyed a 9 color rainbow using fuschia, turquoise, and golden yellow with just scant amounts of dye powder and was able to easily dye 2 yards of fabric.
I was attempting to get a very mottled look for each piece so I tried different ways of scrunching or folding or twisting the fabric before placing it in the dye solution. And while it was suggested to let the fabrics cure for 3 hours, I left them overnight (about 12 hours).
I love the results, but will certainly have to do this many times more to find some consistency.