Please forgive me, but I'm not trying to be a smart ass. Just to clarify, do you mean you've bought Tamiya's acrylic thinner, and you'd like to know what paint to use? I use Tamiya's acrylic thinner X-20A with Tamiya's acrylics only (X/XF series). I suppose you could try using it with other brands and media, but there's not really a reason to, that I can think of. For example, I would not use it with any water-based acrylics, like Vallejo's Model Air or Model Color, Lifecolor, or the craft store brands Apple Barrel, Americana, Folk Art. I use water, or isopropyl. And I don't think it'll work with enamels or lacquers.
As far as thinning the Tamiya paints goes, I start with a 1:1 ratio, and add more thinner as appropriate. I just mix the paint and thinner in my airbrush's paint cup. I eyeball it. I don't use retarders or any other adjuncts, so I can't speak to those.
You can thin Tamiya's acrylics with lacquer thinner, too, though it's not necessary. I have tried it, on a suggestion that lacquer thinner makes the matte colors an absolute dead-matte flat. I didn't really see an effect.
I hope that helps!
Best regards,
Brad