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.
Still if that sounds at all appealing you might first want to stop and ask yourself some questions. Or at least think about these points which can help you decide among the many hair color options. Since the goal is find out which will actually work out best for you and your hair.