I'm in the planning stages of finishing my (Minnesota) attic, starting of course with the problem of insulation. I've determined to install soffit vents w/rafter vents leading up to ridge or gable (yet undecided) vents, then insulate with fiberglass (most likely) up against the underside of the rafter vents. The one thing I have found very little of is advice on installing rafter vents... are the standard polystyrene channels pretty much the way to go, how airtight should they be, do they need to breath, are there any common mistakes, anything. Or is it just that they're so straightforward that nobody finds them all that interesting to talk about?