I start with some spray on primer. I don't think primer is magic. I don't think you must have to prime every model because it holds the paint more. Up until now, all the other pieces on this blog have not been primed with spray or otherwise. But I do it now because I am lazy.
I like this color of primer, Necrotic Flesh from The Army Painter.
Once primed, I tend to start in relief with the inside and work out. The skin, a prime candidate.
The base, another.
I also tend to get the sloppy bits out of the way sooner than later.