Blind dates by nature are a bit absurd: You're expected to spend an afternoon or evening with someone you've never met before and enjoy it. So don't take the situation too seriously. That way, you'll be ready for anything, and you'll be able to laugh about it even if the date turns out to be a dud.
You don't know what to expect, so why expect too much? Just go with the flow when you get there and hope that you have enough in common to carry a conversation. Ideally, the two of you click and it's a match. The worst that can happen is that you just don't hit it off, which really isn't that bad.
Try to think outside the dating box when deciding what to do on your blind date. Rather than just a dinner, which puts a lot of conversation pressure on both of you, go to the zoo, a fair or an art show. These alternative date ideas are often more fun and they ensure you always have something to talk about. Plus, if you're not hitting it off, at least you aren't staring at each other awkwardly across the table.