There are a few things that you need to look at when designing a badge, the following will help the process;
Make the font big enough to read, nobody is going to put their nose close to your badge!

Punchy, short message, make those few words COUNT! "Save your School", Help our Church"......

Images that can be seen, don't choose detailed images to make your point, people won't see the fine detail

Make it a simple clean design, white is GOOD!

PROOF your work, spelling errors will divert attention.