Here's a vegan flier that I made:
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Since this is a bit wordy I usually put it up in places where I can expect a captive audience, for example public restroom stalls, slipped into free newspapers, and other places where people are likely to be waiting. They also make great materials to hand out while tabling.
For other things like public bulletin boards I usually use materials from Vegan Outreach, which can be found here.
Occassionally I'll mix some of these materials up with materials from Peaceful Prairie Animal Sanctuary as well:
Let me know if you try any of these materials out and what works well for you.