A really excellent guide on Liquid Rit-dyeing dolls

(It's over on the Feet of Clay dolls blog on the sidebar, and worth a visit any time.) Especially valuable in this tutorial is the reminder to make the dipping wire or string long enough the steam won't scald you!

http://feetofclaydolls.blogspot.com/2015/07/how-i-dye-resin-part-2-natural-skin.html

(This is hints on color mixing)

This is the dyeing and troubleshooting:

http://feetofclaydolls.blogspot.com/2014/06/how-i-dye-resin.html

And yes, you really do need to sand the doll all over. Small parts take dye faster.