Damaged weatherstripping and caulking should be removed and replaced with durable materials. Use horizontal windows instead of vertical windows. Good window designs start at a minimum of three feet off the floor and end a maximum of six to seven feet from the floor. This design allows people to see out of the window while sitting or standing. Windows should be operable.
Casement windows ventilate better than awning or jalousie windows.
Jalousie windows are the most difficult of the three to seal. Double pane windows are only recommended where outdoor noise is a problem. Limit east and west windows. Try to shade any necessary east and west glass with shutters, solar screen or landscaping. Outside treatments keep out more heat than indoor treatments and save you the most money.