Actually, if you are teaching, or doing this for yourself, this one probably should come first, but I thought the one I posted first seemed a bit more interesting, and, well, eye-catching. Not to mention that I don't really have any images of my own to post here (but I will soon post a collaboration with another one of the contributors here which was made on these principles). Again, this was prepared for an experimental-comics class.
Take a stack of index cards, a bottle of ink, and a mark-making tool. It's best for purposes of this exercise not to get a tool that makes too exact marks, so I'd suggest a sumi-e brush, a dip stick, the dropper from the ink bottle, a rolled-up paper towel, or even your fingers. Make a variety of (abstract) doodles (preferably simpler than too complex) on the blank sides of 24 index cards. Important step: let the ink dry! Then spread all the index cards out before you. How many principles of sequencing can you find for them (sequencing keeping the cards all in the same orientation, i.e. either all portrait- or all landscape-oriented)? You can go from the one with the least amount of marks on it to the one with the greatest number of marks (from white to black, as it were). You can go from the one with the most static composition to the one with the most dynamic composition. You can go from the one with the most horizontal marks (if applicable), to the one with the most vertical marks, etc. When you do this last one, keep in mind that by flipping the cards 90 degrees you can have the marks go up, rather than down (or vice versa). Choose what orientation works best.
Go on to create, based on the same principles, not a simple progression but a formal arc. Go from static to dynamic back to static, and so on.
Let's look at layout: try a variety of formats, beginning with a six-panel page. Choose a sequencing principle, then organize the page also by paying attention to non-sequential (paradigmatic) panel-to-panel relationships. From the remaining cards, make another six-panel page based on the same principle. Make a third, then a fourth. Do the later ones work? Do they possibly work better than the first, because the sequencing principle is not so obvious?
For the final exercise, organize the 24 cards into two 12-panel pages. Make sure to give as much attention to page 1 as to page 2, so, if page 1 works perfectly but page 2 is a mess, you may have to sacrifice part of page 1 to use some of those cards to fix page 2. Once you have settled on two final layouts, tape or glue the cards to a larger piece of paper, then feel free to add marks or remove them (with whiteout), to obtain the most satisfying sequence and layouts possible.
a) begin with a 16 x 24 piece of paper (an 18 x 24 page from which you cut off a 2" strip). Make marks all over it (including going over the edges). Then cut it into 4" squares and proceed with the exercise as before. This allows you to turn each square every which way, and the marks will have more consistency. Only constraint: panels should at no point end up side-by-side in exactly the same configuration in which they were in the uncut piece of paper.
b) for the final exercise, don't make two 12-panel pages, but only one, choosing the best-fitting 12 cards.
c) as a possible take-home assignment, re-draw the final page on a piece of Bristol board, making any changes you see fit to make it work as an abstract comic.