Hi Roy!
The main thing in mixing any paint is to have the consistency of milk! How much thinner for lacquer and enamel reducer for enamel paints depends on the thickness of the paint. Enamel has more pigments, which makes it um thicker?
Your local hobby shop should carry some good paints, Testors, Model Master and Tamiya!
I use a few things for masking; I use Frisket paper sold by Badger, Hobbico Master Mask liquid and fine line 3m tape.
When buying thinner, I buy it by the gallon normally about $25.00 (the good stuff) by PPG or Dupont and the best one but pricy is HOK Thinner.
What airbrush did you buy?
Hope this helps a little.
Manny