How did it go ?
Really useful advice above. I similarly had an airbrush for years before recently plucking up courage to use it, and only after reading the books by Welch and Dent referenced above. I use acrylics, and combo of air brushing and dry brushing. One suggestion not noted above - rather than launching into weathering locos or wagons, I found it easier to start with air brushing an inconsipcuous area of track (ballasted) and some scenic areas of the layout. That allowed me to build up my confidence and the "feel" of the airbrush controls, and then move on to locos, like this '58'. Good luck!