^ lol @ people who didn't read the credits to Banksy
Banksy is epic, I love his work. Definitely a good guy to get the idea of how political/social art is done, too.
I love this kind of stuff. Honestly I'd probably first just do my homework and get to know some artists and their work. You could also look at satirical works, since a lot of this sort of artwork uses satire (but not always). For me, looking at other people's work is a simple way to get some inspiration/ideas.
Since art is all about expression, it helps if you tackle a social/political issue you personally actually care about. The more the better. And since you guys have no restrictions, dang does that give you a lot of breathing room. Since censorship is apparently not an issue here, be as blunt or explicit as you need to be, imo. I would.
Think satire, irony, allusions, metaphors, and all those nice figurative goods we all love.
Oh look, here's a simple example relevant to createBlog:

Credit goes to member #29, as far as I know.