Primer Paint Suggestions???

[SentinelPrime]

Alright...I need advice on what kind of Primer paint do I need to use on a figure before I repaint it?

And how many coats of primer will it take before I'll be ready to to a repaint?

And how long does the primer need to sit before I start repaint project?

***I didn't use a primer on my repaint of Metrotitan, problably should have, this is why I'm asking!