hey, i'v been told that 20 drop's of white and one drop black will do the trick..my want to play with that a little, i'v not done it yet, but the guy who told me this IS KILLER WITH A BONE LOOK,..shake well =p
it also depends if you are talking about realistic bones. Than that would depend on how old and decayed the bones were best thing to do is get a picture of actual bones from dig sites to displayed and use those to mix your colors.
I use purple, green, blue, and grey for dynamic colors. If its a smoking skull(cigarette, cigar, etc.) there may be orange, yellow and red.
For realistic, I like the recipe above but also think you could substitute yellow for the black and get a good look too.
you gave different advice, which is perfect! never feel bad about posting up your experience brother! there is no right way and we are all here to learn from each other the more avenues wer have to explore the better we will all become