But color casts can be corrected without dyeing again if you use filler, which is basically hair-strengthening protein that carries pigment molecules. So I just mix half a bottle of Colorful Professional Protein Filler #3 Platinum ($6) into my hair dye bottle after I've done my roots for 40 minutes, then massage the mixture into my hair and leave it on for 30 minutes.
The protein filler kills the orange, smooths hair, and helps color last longer. And when/if things start getting a little brassy, you can just grab the rest of the bottle and put it directly on your hair for 20 minutes to repair the hue. Let me know if you have any questions about this stuff, or self-blonding in general, and I'll do my level best to get you the info you need.