In the past I have had highlights so much that my hair looked blonde, but the maintenance was a you know what - time and money, so I opted to color my hair back to its natural hair color and then as my hair grew out I'd stay "natural". Well once I went au naturale, I realized how much gray hair I had and I was only 27! So needless to say, I have been coloring it myself ever since, and it looks very natural. The only time I realize I need to color is when I start seeing lots of gray - not because the hair color looks different.
I use L'Oreal Nice and Easy. I have one shade I typically use and like, but have been known to go up or down a shade if they don't have my usual. Finding the right color really is the hardest part and it took me a few tries until I found just the right one. The others didn't look bad but I didn't care for them as much. I tend to be very messy coloring my hair - so my recommendation is to wear something that you won't mind getting hair dye on - I usually wear an old tank top. And clean up any dye you may get on the counter, floor, etc, (told you I'm messy), as soon as you are finished applying it on your hair. Oh and I like to use a comb to spread the dye through my hair a little bit better. Seems to help, although as I am growing my hair out and it's getting longer, I notice I use a lot more dye and it's a little more tiring. But still worth it when I think of the time and money I save at a salon!