150 to 165 grain FMJ bullets are good plinking bullets. Better accuracy can be gained from a bullet whose jacket covers the base of the bullet but they do get a bit more pricey.
Generally, 180 grain bullets are considered a recommended maximum weight for a Garand. There are folks who load bullets as light as 125 grains and get good accuracy out to several hundred yards with a bit lower recoil.
There is a range of powders whose burn rates are around Varget, H4895 and IMR4895 that are appropriate for the Garand. I use H4895 primarily so I forget the upper and lower limit of the suitable powder.
Current commercial 30-06 hunting ammunition uses slower powder than suitable powders for the Garand and these need the adjustable gas plug. The problem is the port pressure remains too high with these slow powders and you run the risk of bending the op-rod. (Note, the op-rod is designed with bends in it, high port pressure bends it out of spec).
Master Po's Temple from the NRA (
http://masterpostemple.bravepages.com/M1load.htm) has good information on Garand loads.
Hornady's reloading manual has a section on Garand safe loads.
There are some other good sources for loads, frequently listed as loads for gas guns. If I remember, Sierra bullet has a section in their manual. Accurate powders used to have a gas gun loading section before they were bought by Western Powders. I have not seen gas gun loads for Western powders, but I have not looked either.
The CMP forum is an excellent source for all information on Garands.
http://forums.thecmp.org/index.php
Enjoy your Garand.