Praetorian

Hello all! I am getting back into model building at age 34. I haven't built a model since I was a kid but I am loving the hobby all over again! I bought an airbrush and used it on a WWII warship to paint some flat colors. It worked great, so I am trying my first glossy airbrush job on a car model. What ratio to thinner do you recommend for a gloss coat? Also, can you use regular Testor's model paint in the airbrush? Thanks!