well i am currently growing out about 4 years of dying my hair myself. My roots are about halfway down my head. My ends look like they are about 5 different colors. i was told to stop dying my hair because my hair was thinning. But I also heard rumors that hair loss can come from being a diabetic.
Whatever the case, my hair has gotten really thin so I am trying not to dye it again. I have been everything to super dark brown to bright auburn. Dark auburns tend to make my hair purple. And I have been doing those Loreal dye and highlight kits. Expensive, but they work well.
If you are gonna dye, do it professionally. I have been dying out of a box for years and I always tend to screw up something.