Mr Color are described as a "solvent based acrylic". They are not a conventional acrylic and are not miscable with water or alcohol like Tamiya and Gunze aqueous acrylics.
For best results, use Mr Color Thinner. Tamiya lacquer thinner or Mr Color Leveling thinner (which contains added retarder). I haven't tried it myself, but I velieve they are also somewhat compatible with generic lacquer thinners. Note that the aforementioned proprietary thinners are "cooler" and are formulated tof ue with styrene.
I haven't tried brush painting with them, but I would imagine it needs a decent whack of thinner - I'd try one part thinner to three parts paint and see how that goes. Do not paint straight out of the bottle - decant some paint to a palette and add thinner.