I keep a supply of Frost King window plastic. Comes in various sizes, has a roll of tape in each box. It's a pain for one person to install, but it can be done. After it's up, stuck well to the tape, you wave a hair dryer over it to shrink the plastic. (Don't get too close with the hairdryer.) Ends up clear and you can see through it like a regular window. I install mine on the side of the window casing so there's a good 4-5 inches of dead space between the window glass and the plastic.

https://www.frostking.com/products/window-kits/indoor-shrink-window-kits

Usually can be found at Home Depot and Lowes, but get it in advance each winter season. (In my area they go fast, once they're put out.)

Also, I think I saw a couple of other brands, but I'd never buy anything but the Frost King. Walmart used to carry another brand, but I never tried them.

It's not too late this winter to put it up, if you can find it. You'll be shocked at the change in room temperatures and at the wind the plastic blocks that's coming through your windows.