I have found helpful the inverted triangle - square - square - square - triangle diagram when I am writing a paper. In the introductory paragraph the writer should begin with a very general statement. They can relate their topic to the world or to all people. Then the writer should be more and more specific. The last sentence of the introductory paragraph should be the topic sentence that clearly states the writers main idea or point. The initial sentence is represented by the wide part of the triangle. The topic sentence is represented by the tip of the triangle.
Then the squares represent the paragraphs where the writer reinforces the main point. Each sentence should be connected with the other in some way. When a new point or reference is being made then a new paragraph should be created. The points should be linked together by the previous sentence.
The closing paragraph should begin by being very specific and restate (albeit, in a different and interesting way) the writer's topic sentence or main point. This is represented by the top of the triangle. Then each of the following sentences should get more and more general. Finally, the last sentence should apply the writer's main topic to the world in a very general way. This is represented by the bottom or wide part of the triangle.
Swales and Freak offer a lot of helpful tips but the topics they suggest to be written about seem quite difficult. I do not know that much about science to elaborate about technical topics. Trying to define humor seems to be a challenging task.
I have found the "Writing Exercise" helpful. Just writing for 5 minutes about any topic or a specific topic seems to be good practice. I suppose writing about a topic that is difficult (science or humor) could be helpful. It would be painful but good for you, like exercise. After writing about a difficult topic and then taking up the task of writing about something that one is familiar with or interested in would seem easier and refreshing.