Air moves in and out of your home through every nook and cranny it can find. The majority of the air escapes through the ceilings, walls and floors of your home.
The easiest way to stop the escaping air is by insulating those areas. Take a look up in your attic, if there is less than R-22 (7 inches of blown in insulation) then you would benefit by adding more. The recommend R-Value for the Omaha area is R-49 for attics, R-25 for floors, R-18 for walls, and R-19 for crawlspaces.
Insulation comes in 4 basic types. Batt Insulation fits between studs and joists in the ceiling, floors, and walls. Rolls or blanket of insulation lay over the floor in the attic. Loose-fill insulation is blown into the attic or wall spaces with a machine that you can rent or use free of charge from where ever you purchase your insulation from. Last is Rigid Foam Board insulation used in confined spaces like exterior walls, basements, foundations and crawl spaces.
Insulate crawl spaces walls only if the crawlspace is dry all year, the floor above is not insulated, and all ventilation to the crawl space is blocked. A vapor retarder should be installed on the ground to reduce moisture migration into the crawl space.