You have dirt on the tires already, that certainly is a good start.
Barker Pass, Ellis Peak on Tahoe's west shore are good tune-up riding places before tackling the Rubicon Trail. Try the legal motorized section of Tahoe Rim Trail on east shore between Spooner Summit and Kingsbury Grade where Mark Twain quickly decided journalism in Virginia City was a might easier than cutting wood timbering for the Comstock. Fun ride. Also some challenging ( steep & loose) singletracks there that drop down from there to towards Carson City, may have to take HWY 50 to climb back up to the basin though as they can be a little steep, loose and technical when riding solo.