I know the distinction is getting lost in recent years, but there's a difference in "accessorizing" and "gunsmithing". Also a difference in "servicing" and "gunsmithing" as well.

As I mentioned before, the SKS has huge aftermarket following, so accessorizing it will be incredibly simple. Also as I mentioned before, buy a few books on gunsmithing and watch Midwayusa's youtube videos. If you want to get serious about hobby smithing, beyond simple accessorizing and detail stripping (disassembly and reassembly), then these would be the places to start. Then if you want to get serious about gunsmithing, apprentice under a machinist or master gunsmith, and then go to a proper gunsmithing school.