Garmin put a lot of time and money into making those desktop sims and at $25 a pop they worth their weight in $50 bills. Some PCs have trouble with some of them however, and yours may crash. I have had great luck with the Cessna piston sims, but my CJ sim runs like crap and always did. Nobody can figure out why. It boots up slow and generally freezes. I have talked to numerous computer geeks about it, and nobody has a clue. Change the drivers, disable this and that, they have no idea.
Once your fingers are worn to bloody nubs practicing at home
take a day back for healing, then get in a classroom and hear the certified lecture series on the system. The system is complex enough that just being proficient in switch-ology is not enough. You need an experienced teacher to give you various the details on how the thing operates and what the best practices are for operating it. Classroom is the way to do this.
Next go fly. Do flights covering
• busy airspace work, air work, unusual atittudes, emergencies
• approaches and IFR use (several flights for this)
• night use
• heavy weather & cross country use (nexrad, flight planning, etc)
• how to instruct using the system if you are a CFI
The more I think about it the more flights I can justify putting in my list, but ten flights would seem a bare minimum for a newbie. It is a complex avionics suite to be taken very seriously. I am not teaching on the G1000 now, but I was a certified Garmin G1000 instructor at one point and my VFR students routinely took 20+ hours get comfortable with the system only doing VFR tasks. Instructors and IFR pilots will require many more.