for my self - playing around in the FSX + Wilhelm Thaller's book "Never Get Lost" didn't do any harm, I also bought "VOR Tracker" app on the Google Play (Android) to practice intercepts and holds. Finished the course in minimum time and first time passes. Flying is expensive as it is, I would definitely recommend going to the sim/aircraft already knowing basic principles of instrument flying. If you, like other posters here, can afford to burn cash by going to a lesson as a blank page, that's fine, you can do that as well. I was not so fortunate