How to determine mod sets?

So not this month but next month i should be unlocking Rey DSV, and I was wondering how do I determine a good mod set for a character?

Her mastery increases crit damage and crit chance, while her unique gives her 100% max health.

Am I right to think that I should be aiming to give her CC/CD sets with health prinaries based on that knowledge? Or am i missing something?

Should I use skills other than mastery to determine mods. I typically use whatever .gg suggests or what hotutils pushes for mods but this one i want to figure out (mostly) on my own