To begin with the choice of colors would top the list. So what family of colors is on your mane wish list? Are you looking to alter the color or color the gray?
Coloring tip: It's a fact. The longer your hair is the older the ends are. Okay no news there. What may be news is that this makes them more porous and open to accepting hair dye. Which is why you want to get to them last if coloring at home. Otherwise they may end up darker than the rest of your strands leaving you with a final result that is well, interesting looking. Just not in a cute and sexy way.