1. Your illustrations look clear, sharp, and easy to follow.
Agreed, they are quite clear...but they look flat and two-dimensional. Try either (or both) (a) adding some shading in relevant places to suggest three-dimensionality, or (b) emphasizing underlying layers by making them slightly offset from the overlying ones--it looks like you've tried this on the two stretched flaps in the middle of the model, and how they connect to the rest of the model on the top and bottom of each diagram, but I can't zoom in clearly enough to tell for sure. I also recommend making the existing crease lines thinner, but the idea of making them a lighter shade on the darker background is a good one! In a few places (the minority, to be sure), the existing crease lines look like they go all the way to the edge of the model, which of course they should not.
2. I prefer the Left to Right style of flow, instead of the continuous flow... my opinion... and it probably is a less efficient use of paper, but I think it is a little easier to follow.
As a general rule, I agree with this; I don't usually like the "follow the yellow brick road" approach, but of course with some models and diagrams, using a grid-like layout is the only way to pack a larger number of diagrams onto a single page. If you must use the "follow the yellow brick road" approach, I recommend making the step numbers much larger and easier to see at a glance--try divorcing them from the text instructions from each step and moving them to the upper left of their associated diagrams.
A slightly larger line with twice the space might be easier to see. And a serif font, like Times would be easier to read.
I don't know what you mean by the line and space thing, but I disagree about the serif font. Standard practice in graphic design, as I understand it, is that sans-serif fonts are easier to read than serif fonts, especially at small sizes. Of course, this depends on the font, too--I'd agree that Times New Roman is easier to read than, say, Echo, or even Bordeaux Heavy, but simple sans-serif fonts, such as Arial, Gill Sans, Tahoma, Eras, etc. are the cleanest, easiest-to-read fonts. Boring because they're overused, to be sure, but clean and easy!
On a tangential note--and this is not necessarily something that you should change in your diagrams--I've never understood why some steps are given sequential numbers in diagrams when no action happens between them. For example, in steps 22-23 of your diagrams, nothing is happening in the model. Yet the model now appears to be one step longer than it needs to. Granted, this is common practice in diagramming, but I've never understood it. I could diagram making the traditional crane, showing the model at different magnifications, from different angles, etc., and make it a 100+ "step" model. But different magnifications and views aren't steps; they are different aspects of a single step. There are at least a couple of workarounds for this:
(1) using letter suffixes that provide an additional means of informing the reader that two sets of diagrams are related but not necessarily different. For example, instead of 22-23 in your diagrams, make them 22a and 22b.
(2) Don't number intermediate steps at all. Interestingly, you've done something similar with your step 29--just providing one label, and one step number, to two (or more) different diagrams that show two (or more) different views.
Either one is fine, really, but you've got two different methods going on: how you did step 29 is inconsistent with how you did steps 22-23. This won't confuse any readers or followers of the diagrams, but it does come across as a tad sloppy, as well as not giving an appropriate number of steps for the finished model. (But for that matter, I've never gotten a good handle on whether or not people include a single diagrammed step that says "Repeat steps 18-63 on the other side." as
one step in the finished model or 45 steps!)
For whatever it's worth, here's the diagrams I whipped up for the Prehistorigami exhibit on how to fold the traditional crane. This aren't actually the final version, but one I came up with in the process of trying to avoid reverse folds (for some reason, those seem really unclear to novices), so there are more steps in these diagrams than one might expect to see in "real" origami diagrams, but I didn't number the "intermediate" steps. I also could have added a tad more shading to some of them to indicate where some layers go beneath others, but didn't for the sake of expediency (deadline was approaching!).
(larger view
here)
I'm not saying these diagrams are perfect; merely providing a point of comparison!