[Tell It Right]

I agree wholeheartedly and have done most of those things (at least the things that gain value here in the south, since keeping heat from escaping through the roof ain't much of a problem here since that's often a good thing).

One problem we have here is the power utility, the Southern Company, is very much in bed with our local governments. Competitors can't start up here.

[woodbutcher1963]

You can also gain heat through your roof IF you do not have enough insulation.

None of the things I mention make a big difference except insulation. However, cumulatively they make a huge difference when you add them altogether.
They certainly did on my 1972 house. I added insulation, replaced doors, caulked, planted trees and insulated drapes.
I have Pella windows.

One of the simplest things is just insulating around electrical outlets in your exterior walls and ceiling with spray foam cans.

Another thought is adding lighter colored metal roofing. Metal roofing can reflect the sun instead of dark colors that absorb the sun.