Install collar beams to create a space under the ridge["false ceiling"] for air to flow from the louvered gabled end vents at the ends out the through the rafter vents and eaves[ Rob's idea].Install ample insulation over the vents in the rafter spaces and between the collar beams. If you have knee walls [or install them] insulate them.
I don't have the computer skill to draw an illustration. But here is a photo of my attic ceiling which has collar beams installed to equal the cu.ft.size of the gable end vents[ I also installed a ridge vent when reroofing for hail damage this year.
Think about lighting. My attic room is on the upstairs HVAC system and returns through and open door to a intake vent right outside.
I just realized that I don't have photos of my ceiling, just one my wife took to show what she refers to as "the mess". But you can at least see the narrow ceiling created by the collar joists and the beginning of flourescent lights running end to end.
