I gotta agree with vrai.
It doesn't take a rocket scientist to be a bartender.
I have done it several times.
The best thing you can have going for you is to be easy going and listen to what people say. They don't care if you have to look up a drink in the book. They are mainly concerned that you are friendly, outgoing and willing to lend an ear.
Really, I had some good times tending bar, and this was in some rather rough joints in the south. Just be good to the customers, don't take any sh!t and let the people have a good time.