Fundamental to any good scale model paint job is good preparation work so that any accidents you experience are "off model" and not on the scale beauty you have just spent a couple of months perfecting.
If you are just getting started with airburshing put together a system that will make your painting go easier every time you do it.
Pulltogether several of the same sized containers for paint mixing and make a gauge mark at the same level on each so you can easily determine equal quantities of paint for each job.
Buy some disposable pipettes from an online chemical supply house. With these you can add precise amounts of paints and thinners to your mixes.
Important--cut several sheets of styrene into one half by one inch pieces. Prepare them the way you will your models for painting (wash with mild detergent, sand and prime) to use as test pieces.
Shoot a series of these test pieces, changing one variable of your painting process at a time. (Try thinner paint ratios, change distance from the part, vary the airbush pressure, change needle size etc.)
Just before you actually paint the model, paint a few test pieces to get an idea of how long it will take to dry and become compatible with top coats. If your model provides you with an inside surface that won't show, try a small area.
Do your masking with painter's blue masking tape. This is a 'low-tack" adhesive which will minimize the risk of pull-off and edge bubbles.