Well, the first thing I do with CMP guns is to check the headspace and do an all around inspection of the rifles. The rifles are oiled and I remove the oil and apply grease to the wear points, rails, ect. I also preform the tilt test, and check timing.
The tilt test you can do your self, timing you may be able to do if you have the gage. Diffentily check the headspace as it could be dangerous to fire the rifle if it's not within spec. Timing isn't all that important for the first firing and if everything works fine when you fire it, you'll be good to go.
Get your self some grease and grease the rifle up. I would strongly suggest that you go to www.jouster.com and spend some time reading lane's tips and the boards there. Jouster is the AR15.com of the garand world.
Oh, you do know about what ammo you can feed your garand and what to stay away from right??
Anything else you want to know, IM me. Good luck.