Traditional introductions are comprised of three parts: the hook, the background/context, and the thesis.
The hook functions as an interesting opening to the essay designed to "grab" the reader's attention and provide a stylistic lead. To be effective, a hook should be original, interesting, and consistent with the essay's topic and tone. Some forms effective hooks may take could be a question (either rhetorical or literal), definition, description, anecdote, fact/statistic, or an example.
The second part of the introduction introduces all of the necessary background information to provide context for your analysis and argument. Here is where you need to introduce (define and explain) your key terms and ideas. In the case of this essay, you would need to introduce the idea of photography and then whatever concept you are focusing on to make your argument.
The third and final part of your introduction is where you present your specific argument about the topic. The thesis statement will vary; an effective method to craft a strong thesis would be to return to the questions you posed in the last blog post. Find the one question that seems to be the most important or significant. Then, write an answer to your question; that will be your thesis. As you are writing your thesis, do not reduce your argument to opinion by writing "I think" or "In my opinion." Instead, just present your argument objectively.
For this entry, post your introduction to this blog. These introductions should be a solid paragraph that would entail somewhere between half-a-page and a full page if you were to type it in a double-spaced essay.