creating the correct mix for acrylic thinner

this site here says to use 91% isopropyl alcohol with Tamiya acrylics. 

http://www.fichtenfoo.com/02GiantRobots/02c-MGHowTo.html#Painting

I've heard the same on the 91% alcohol thing... I also know some on here have used lacquer thinner with success, but that's a little scary for me to try on an expensive kit!  You could try adding a drop or two of retarder to your mix to slow down spraying time if the results aren't what you expect.  (i.e. excessive tip dry or grainy paint finish)