Unless you are for some reason wanting to really get your gun clean,perhaps for storage or just because,you don't need to do much more then simply field strip the weapon and clean it as you would normally clean any other rifle.You do not need to disassemble it any further then that to clean it,only for repair and/or replacement of parts.
When you clean your AK pay special attention to the gas hole in the gas block and the gas block itself.Make sure you get in there and clean it well.Even without corrosive ammo,this is where erosion of the barrel can start and also where combustion residue can build up and cause failure to cycle malfunctions(rarely,but it can happen).
Sometimes,I take a rag and clean the inside of the sight block out where the gas assembly goes,but not all the time.I do clean out the piston tube and clean the piston whenever I clean the weapon,but you do not need to remove your piston from the carrier.
Make sure to use a LIGHT amount of grease on your mainspring upon reassembly.
You can abuse an AK much more then you can alot of other rifles,but it is still a mechanical device and despite its peasant-proof design,it can fail.Not keeping it clean can make failure more likely.
Please clean your weapons regularly,clean guns are happy guns.