Nic concentrate help please

I was vaping 6mg or 3mg juice when we could order it from NZ. Then I got sucked into disposables when the ban hit and I didn’t stock up. Now I’m trying to ditch disposables and ordered some pharmacy juice but I can see I’m better off mixing my own.

I ordered VG, PG, fruit flavour, sweetener and cooling agent but I have no clue about the nic. Do I want salt or fb? What strength would suit? Could someone please help explain what I should order and where I can find it? I’m assuming I need a concentrate so I can add a few drops to a mix?

I don’t mind if I end up with 3mg or 6mg juice, either will be ok. I’m not super fussy about vaping either, I can leave or take a throat hit and I prefer less clouds but I do prefer dtl vaping.

I’m using a new Aegis mini M100 with the Z FLI tank if that helps.

Thank you in advance!