I'm with Music with a roughly 2 or 3:1 Paint/Thinner mix.
I have used this mix with Gunze, Tamiya, MM and Lifecolour, and it has worked fine, giving an even finish in around 3 coats.
Try Tamiya acrylic thinner, as this contains an inhibitor, which slows down the drying time of acrylics, making them easier to spray.
Karl