As I see it, linking words or transitions can be used to link from one paragraph to another and also within paragraphs (from one sentence to another). And transitions have kinds such as "addition, example, contrast,comparison, reason..." So only if you can make sure with the usage of each word, you can understand well how to use them in your writing an essay. Talking about organizing ideas, I see that Paul also explained in the discussion room. Please see that. (In introdution, we start with a few general statements along with a thesis/main statement. In body, we divide our ideas into parts by describing them in chronological orders. For example, your thesis statement is about animals, so in the body, you are going to describe a dog, a cat, a mouse...or something else about animals in chronological orders. In conclusion, you summarize the ideas and give a few comments. )
I hope it is useful for u.
