Best advice I can give you is to start with a 50/50 mix and experiment from there. Try different ratios and air pressure combos and make notes.
Since you will be working with acrylics, I suggest a visit to Hobby Lobby or Michaels, grab a 40% coupon and get you self some retarder and flow improver. The retarder will slow down drying, minimizing tip drying in your AB and the flow improver will help the acrylic circulate smoother in the AB. These products will last you a loong time and are beneficial.
For cleaning the acrylic out of the AB, save your thinner and use Windex. I use the one from the dollar store with ammonia and it works just like the expensive one. And only use the thinners made for the particular brand. Don't mix thinners and brands cause all acrylics may not be compatible, specially if using Tamiya acrylics. Another heads up, MM acrylic primers have a tendency to lift when masking is removed. I have found the MM acrylic sprayed over unprimed plastic tend to lift, primer or no primer. I have not noticed this problem with Tamiya acrylics which seem to bite better into the plastic.