I use a very thin coat on the water pump, just enough to cover it. I usually just put a small dab on it and spread it over the entire gasket, put it on the water pump and then repeat for the other side. I use copper spray on the front cover gasket and use a factory mitsubishi one, the ones in the after-market kits are junk IMO.
This is the way I do it and I've never had any issues, I'm sure others have different ways of doing it. This is what works for me.