The introductory paragraph or paragraphs should contain your thesis statement. It usually comes at the end of the first paragraph but can go elsewhere if you have a good reason. The ideas presented in the introduction should be in the order you will present them in the body of the paper. If you deal with one point in two paragraphs, try to use two paragraphs for the other points if possible. Don't add random material just to even up the space used, though.
Many writers write their introductions after they've written the rest of their essays.
It's easier to introduce the material after you know what you're actually saying.