I shampoo it off, with a deep cleanser, and dry off until bone dry. I then drench in a porosity balancer and then dry that in.
Depending on what target shade I am going for, I then decide if I need to pre-pig, but often than not, I don't as I have normally lifted to a coppery/orange shade.
I then go in with my target shade, I always add base and never go higher than 3%. I also give my clients the prescribed shampoo and always finish off with a treatment.
I never have problems with fade or tones becoming unstable. My clients always leave with shiny, glossy locks.