Philocrites gave some advice recently about not using a fine point marker if you're making signs for a demonstration. There really needs to be some information put out there if anything's going to be made of public demonstrations. After all, a certain unnamed rabidly anti-gay wacko from Kansas has signs so bold they could be read from space.
This gets me back to a pair of very practical websites that deal with related issues, each related to sign making, and by extension, banners at General Assembly. I'd love to see a moratorium on rainbow color themes, shapes of river course, and illegible writing on banners. (Yes, I know a banner and a flag serve different purposes.) I think the best banners are those that, like flags, have a simple color scheme and a memorable design. My favorite here is the Muttontown, New York congregation, which has a big, recognizable sheep on theirs. I also like seeing the "flaming crab" of the Annapolis, Maryland banner.
In short, if you can't recognize a banner from a thumbnail, how in the world can someone recognize it from the rafters at the Opening Ceremony or when hung up?
The North American Vexilogical Association has good flag design advice:
Good Flag, Bad Flag: How to Design a Great Flag
The other site is from the Letterheads with old fashioned instruction about hand lettering, as once used widely for commercial applications. Calligraphy's larger, plainer cousin.
And remember, in some areas, the wooden pickets used to hold signs aren't allowed, as they can be used as a weapon. Cardboard tubes may be substituted.