One other thing not mentioned yet is thermostatically-controlled attic
ventilation. Works great for me in SW CT, so I don't know how you
survive without one from June to October in TX.

You can get a fan and t-stat pkg for $100. Took me a couple hours to
make up a transition from plywood to attach it at gable. Effect is
clearly noticeable in mid-pm temps on floor below in Aug., and shingles
should roast much more slowly. Just be sure you have adequate inlet
area. (Insulation is below attic floor in my case- you want to vent
above the insulation.)

HTH,
J