I want to iterate what's been mentioned above...
NO LUBRICATION INSIDE THE BARREL GROUP
So that includes hop unit, bucking and barrel. Oil or grease in these areas will negatively affect the ability for your hop to apply backspin (as you are lubricating a part that relies on friction) as well as cause inconsistency in bb flight and accuracy. To add to that, any debris that comes into contact with those inner parts will stick inside and cause issues. A bucking will wear out eventually anyway, it's a sacrificial part, so no need to oil it.
Clean your bucking in warm soapy water and dry naturally. Rubbing alcohol to clean the barrel. It should all be dry as a bone when you use it. Clean your barrel and bucking regularly. I do it roughly every thousand or two rounds in my AEGs, at a guess. If you're using bio bbs, then do it after every game.
Lubrication-wise it's really simple. You can use silicon or Teflon grease. Inside the box use just a little on the gears, cylinder head and piston o-rings, piston races and trigger trolley. Don't smear loads in there either. Don't ignore a touch on the motor pinion either. You WILL need to get inside the gearbox to lubricate periodically as that grease will dry up and your box will suffer, including drying/cracking o-rings and increased wear on gear teeth. Like any collection of moving parts, lubrication and servicing are important to maintain durability, reliability and lifespan. If you don't like the idea of doing that yourself, a technician will be able to help you.
Anywhere else is just to prevent corrosion on any bare metal parts, so just a squirt of silicon oil and rubbing it over the externals is fine. Normally only needed on exposed steel.
nothing at all to get too confused about. Just remember to keep that crap out of your bucking and barrel!