Dying hair from dark to light brown.?

Kally Asked: Dying hair from dark to light brown.?

I have very long healthy hair that I dye regularly ( once a month) a dark brown color.I buy my products from Sally's.The first time I dyed it this color was Sept.I used a 10 developer and a level 4 dark brown.I liked it but decided it would ultimately be to dark to keep up with ( my hair is a dark ask brown that I feel i far to bland).After that I decidedto go with a 20 developer and a level 3 dark brown.I'vedone that twice to do root touch ups.Now I would like to lighten my color a little more so I don't notice my roots so soon.I was thinking I could use a 30 or 40 developer and choose a lighter color of brown.I just wanted opinions from someone else who has been through this similar situation or who knows alot about hair! I appreciate any answers in advance!

P.S.I am not looking to go to a salon, though I know that is an option.