After talking to many pretty good painters here, they all recommended epoxy primer. I was kind of surprised thinking self etch was the key, but most agreed self etch is not as good on chrome as epoxy.
I guess the term "self-etch" lulls people into believing it will etch into chrome.
It sounds like they use 36 grit grinding discs (and all warned me about heat warping the metal- keep it moving and short, short grinding bursts) to tooth the chrome really well, then scrub down with wax and grease remover, then epoxy. Then 80 grit the epoxy (but dont break through) followed up with a sealer, then high build primer over that. Then its block sand and paint/clear coat.
I have painted cars in the way back, when things were easier (fewer steps, fewer choices). Now it sounds like there are 5-7 steps, with 10 to 20 choices for each step, and one bad choice can ruin the job. Pretty confusing really.
(but the paint jobs of today are spectacular compared to 30 or more years ago!)