Flyers and other printed materials
Less text is better. People will typically read for a few seconds and then ask you to explain. The title should be easy to read and let people instantly know if the flyer interests them or not.
Flyers should have a clear call to action: show up to an event, or scan a QR code to send an email. We use https://mailtolinkgenerator.com/ to generate QR codes that can send pre-written emails.
If possible, make flyers for a specific event. For example, a flyer aimed at a bike-riding audience might be able to assume the audience has more background context that one on a slow street.
Printing flyers (etc)
You can probably print out a limited number of flyers at your local library and cut them up with scissors, but it can be useful to find people who own a printer (and maybe even a paper cutter) and who can produce flyers on short notice.
Make sure that your flyers have enough of a margin that they don't get cut off by the printer. If you're cutting them into 4, having a good margin on the part you're cutting is also good, especially if you're cutting a bunch at once.
Print one sheet of flyers first and make sure the margins work and it's formatted right before printing a bunch more.
You can also get blank stickers from your local office supply store that can be printed on. If you have a home printer, there's probably a separate feed you can open to print on non-standard sheets of paper.
You'll generally want signs at most of your actions. You'll often want to reuse them and keep them on hand. Getting a bunch of people together to make signs in advance is fun, lets you be more creative, get any small children involved, and get to know each other.
Bring something to attach them to bikes, street poles, etc. Signs can be attached to empty rear bike racks if they are sized appropriately. It's hard to hold a sign while riding a bike. Attaching signs to street poles is something we mostly do for vigils to mark a road violence related death, so that the message remains after we are gone.