Well, I always find these "negotiate your salary" articles very strange because in 20+ years I never did it like that. There is only one rule I follow:

- Get more money than what I'm currently making and by that, I mean at least 20% more

I've no problem telling them my current salary since it's always been in the upper quartile for my area. To get me to switch, the increase has to be significant or else it's not worth the risk of plunging into the unknown and the pain of learning yet another completely different spaghetti mess where generations of architecture astronauts added layers upon layers until the complexity exceeded their mental capacity to maintain it and left.