Hardware stores sell a kind of plastic to put on the inside and heat it up with a hair dryer, sort of like shrink wrap. I don't know what it is called, though.
They have them at Walmart and Lowe’s. Did this to my sunroom windows that were not replaced yet. Makes a huge difference summer and winter.
there are winterizing kits at most hardware stores, the window film is very thin, ok if no pets, but my 4 cats will shred it. Both styles use an adhesive strip to hold the plastic in place. Outlets on exterior walls will need a foam pad placed on the back of the outlet cover. You can still use the outlet, but with less draft. Exterior water hoses need to be taken off the tap and water allowed to drain out. Lawn mowers need the gas either used up or a product like Stable added.some times americor volunteers will bring supplies to you home and winterize you place if you use food assistance programs. If you have a basement, you can get insulation for the water pipes that are very inexpensive.it remind me of a pool noodle, bit with a slit on the side to get it on the pipe. If you have a hot water tank, there are insulation blankets available for them as well.
As noted above there are kits in hardware stores as well as Walmart, Lowes or Home Depot to put plastic over the inside of your windows. You can also run strip insulation foam (it's adhesive) around the windows in the frames to help keep drafts out.