I Made Them Myself, Can You Tell?

If i set out to do my own window treatments, they'd probably be done in plywood and black paint. Can't help it, I'm that kind of man. Thank God, my sainted wife sews, and she sews well. She won't allow me to post a photo of our Roman shades in the "sunny addition" mentioned in earlier posts, but there are lots of places you can go to get ideas and even instructional help. If the sewing thing is never going to be you, don't despair. Other strategies will get you into higher R factors and movable coverings for those windows that feel good all day but not at night.
Rigid panels, made of foam (not plywood, i was kidding) or some other insulating board, can give you a great R factor while controlling radiant and conductive heat losses through windows.
Pre-fab panels can be purchased to your measurements, or you can make panels yourself from insulating board material from the home store. The look can be as basic as the specular silver or black coating on the raw board, or as sexy as the white muslin my wife used to cover ours. Fastening can be as simple as sticky pads from duct tape, or as sleek as store-bought velcro patches. This is good, clean fun and you can't fail, unless you slip with that sharp knife; so watch yourself, go slow, and measure three times.
The least cost option, for people on strict budgets or short on time and craft moxy, is 3M shrink film window coverings, available at the home store and as easy to install as Saran wrap in a static electricity vortex. I made a mess of mine, but my wife calmed me down, and with her help we covered several old, drafty windows and got a wonderful result. The film product goes into place over two-sided sticky tape, and a hair dryer (watch the heat, you can melt the film) shrinks it to wrinkle-free tension, sealing an old window against drafts very nicely. It's not sophisticated, and you can't open the window until you remove the film, but in terms of return-on-investment, it's top of the list. They even make a kit sized for sliding glass doors, if you can do without the entry option all winter.
It doesn't have to be expensive, it doesn't have to be Martha, although i'm sure hers are lovely. It just has to stifle drafts, cut down on conductive losses, and permit the sun to come in and bless you with its warmth during the day. That's why God made windows.