Topical order
When you organize your essay topically, you need to apply the next structure to your essay.
In order to write a good remembering-a-person essay, you need to depend on your memory and portray the person vividly so that the readers can imagine what s/he is like. Close your eyes and draw the person with distinctive characteristics in your mind.
Introduction
A hook sentence: attract your readers' attention with a rhetorical question, a striking image of the person, or that person's particular characteristics.
Provide the background information of the person that is related to the thesis statement. Do not have general information of the person unless it supports the thesis or controlling idea.
Thesis Statement should have one controlling idea. If somebody asks you about that person, how do you introduce him/her in a sentence. This sentence will be a candidate for the thesis statement of this essay.
Body paragraphs
Topic sentence can be one of the reasons of the thesis statement. In order to have a proper topic sentence, you need to ask yourself, "why do I introduce that person like in the thesis?" And then you answer, "Because...." The clause after because will be the topic sentence in the body paragraph. For details, think of what you want to use, for example, a special episode, recurring events, particular traits (personality/appearance), memorable dialogue, and then select efficient writing skills to express them such as chronological order, flashback, and/or comparison and contrast.
Try to have several body paragraphs, which deal with the ideas that you have in the thesis statement.
Conclusion
Use framing technique.
Describe the person's characteristics in different words that you have in the body paragraphs.
Remind another memorable anecdote about the person that supports the thesis.