Here was my inspiration:
Here is what you will need for this project.
* Masking tape (optional)
* Scissors or box cutter
* Storage bin or box
1) Separate your lights into piles and untangle what you can. Surprisingly, most of mine were easy to untangle, so I didn't have to spend a lot of time doing that.
2) Figure out how big you want your cardboard pieces to be. You'll need to make sure that: a) the cardboard is thick enough (don't use thin cardboard that will bend easily), b) they will fit easily inside the box, c) that the lid on your bin/box will close easily, and d) that the entire string of lights will fit on the piece of cardboard. Once you have this figured out (it's not an exact science), cut your pieces with scissors or a box cutter (scissors worked just fine for me).
3) Start wrapping a string of lights around a piece of cardboard. You can secure the end of the string to the cardboard with masking tape (which is what I did) or you can just tuck it into a part of the lights that are already wound around the cardboard.
4) Once you've wrapped all of your sets of lights onto the cardboard, just file them away in your bin or box like I did below.
I didn't time it, but it really didn't take too long for me to do this - maybe an hour and half from start to finish? Also, I noticed that this may not exactly be a space saver - I wouldn't have been able to fit anymore sets of lights, but previously I could have fit 1 or 2 more. However the advantage of doing this is that you can easily pull out a set of lights and they won't get tangled with each other, which is totally worth the time it will save you to untangling them.