Before i set a pan on the engine i see how 'flat' it is and if used i see if it has been over-tight and the bolt holes pulled down - there is supposed to be a slight airgap at the bolts so they can pull down, some people overtighten and the bolt holes get pulled inward so the bolt makes contac befor the rail. I check for 'flat' because it is industry standard that it can 'rock' corner to corner a full 1/4" and be considered 'in tolorance' (as per moroso catalog and instruction sheet).
When i feel i have something to work with i use the 'right stuff' permatex or permatex 'ultra' (i think it is called) and goop up both sides of the thicker 'felt' type pan rail gasket and when i pull the bolts/nuts down i am careful to not overtighten - you are safe as long as the gasket don't push.
When troubleshooting a leak, think about how the oil is sitting in the pan. It ain't nowhere near the pan rails, you will have to be on a pretty steep grade for it too leak out of the lower parts of the crank seal area. Take a pan and dump oil into it and you'll see what i mean. Something is really screwed up if it sits there and oil dribbles out the pan rail, you can pretty much rule that type of problem out. So if it is leaking while sitting it likely ain't the pan.