Welcome to the hobby! The advice from the other two commenters (at time of writing) is fantastic.
Remember to thin your paints - you can always build up layers if they're too thin, but having too thick paint will totally cover up details.
Don't panic if you make a mistake; you can brush off paint while still wet, paint over something after it's dried, or totally strip paint in a number of easy ways if you need to!
Good luck with the emperor's children - super cool model range!