There is nothing to it really. Just rent a space and sell stuff. What's to know?

Come on now. Why the F are you asking that question here? What answer could you possibly be looking for? Have you ever seen those big stores with, (what do you call them?)...Books! Maybe you could read one and then another one. Then when you think you've got a handle on it, read some more.
There, now you've got your advice. Go forth and prosper.