yup, I'd put aero at the top of the list though efficiency wise, as it is the most radical thing to change IMHO and sets the parameters for things like engine size and gearing.
Some of the rest can be adjusted to some degree without a lot of fuss (pump up tires, change valve timing, put small sprocket on rear).
I gotta streamline my bike this year
I get 96 mpg pretty consistently w/pulse and glide, but would like to glide a lot farther @ speed. More aero might take me over 100mpg, hoping for 105.