My situation was this; I have been coloring my hair since 1985 a soft red.  Now years later those pesty greys are popping out at a rapid rate and my color wasn't holding for more than a week  or so.  More than depressing.  Red is very difficult and demanding to keep up.  

 

I wanted to go back to my natural shade of mousey brown (something I hadn't seen since I was 16, blonde to reverse frosting to red over the years, lol).  I let the roots grow out for six weeks so I could really get a good match.  Believe me it wasn't a pretty sight and I wore it up in a scrunchie most of the time. 

 

After reading here I used a package of Effasol-20% developer for 30 minutes to remove the red and then applied two ounces of Ion med golden brown and one ounce of dark golden brown.  I waited until my hair was air dried after using the Effasol.  After doing a strand test I applied the Ion mixture for only 25 minutes. 

 

It turned out great!  Nice golden tones with just a hint of red undertones in the sunlight which is just what I wanted for my long naturally curly hair. 

 

Now when the greys start popping up in a few weeks I will have to think about what to do because I really don't want to continue to color my hair and think I would like to just let the greys come in.  More than 50% now.  Maybe some lowlights????? at the hairline where the greys are really concentrated.  

 

Kudos to all here.  So much knowledge and and helpful people you all are