I've been trying to learn the more advanced techniques - The solver at sudokuwiki.org goes step by step... but what I don't know is how to start to look for things such as simple coloring. The site can use brute force to find such things, but finding how to find is the tough part. With that one simple coloring, everything else fell out like an Easy... but now I want to know how to do that myself.
spellacked --- To me it's trial and error, almost always after greens are used. I sometimes write down the #'s 1 thru 9 and cross out the obvious #'s (those already solved, those with only 2 or 3 cells to fill) You can usually get down to 3 or 4 candidates then and coloring is easier