This question is similar to your last question. If you keep the following few points in mind, then you should be fine.
First, the structure of a successful paragraph is a contained unit. The first sentence or sentences introduces an idea, which you will develop for the rest of the paragraph. For the concluding paragraph of an essay, it will be be a summary of your thesis of some sorts. The following sentences, then should seek the support the summary of your thesis.
Second, craft your middle sentences to support your thesis in creative ways. If you simply restate your thesis with the same words, it will not be successful. Variation with the same theme is the key. Let me give you an example. If you are writing about the importance of green technology, you might write:
As one can see, green technology will be important for future generations. The lack of resources is become more and more evident. Moreover, the accessibility of theses natural resources is becoming dangerously difficult to obtain. In light of this, conservation and the development of new technologies will be the way forward. A new generation of men and women will have to lead the way to a cleaner and more effective future.
I would also like to add to the post above that you need to practice your writing skills in the form of drafting your own essay until you achieve your goal. What is your goal? The goal is to successfully communicate your idea (the title of the essay contains exactly what you are discussing/debating/or simply describing). At all times, read your own drafts with the eyes of the reader not your own eyes (of the writer). This way you will be able to see what words are missing to make your ideas come clearly in the reader's mind. It will make your essay less confusing.
Writing an essay is a combination of knowing the basic grammar-rules of the language in which you are writing, the cultural knowledge of specific linguistic structures, and how you combine those structures to reflect meaning. This is called language-in-use. It is up to you, as individual writer, to find the exact linguistic structures that reflect what is in your mind. In order to find those structures, you need to draft your work as many times as you need in order to find the perfect way to persuade the reader, or to make the reader understand exactly what you have in mind according to the purpose of the essay.
When writing an essay of whatever length, you start with writing the body of it and then you focus on the introduction and conclusion. The introduction states what you are writing about and you can throw a few lines on the ideas that come apparent in reading the whole middle of the essay. Do not reveal too much, just summarize your work. Make the language sound like Future Tense: this is the introduction. When you write the conclusion, the language will sound like Past Tense: you did this, you did that and this is the outcome of all of it. Depending on what kind of style you choose for your essay, your language can sound stronger in expressing opinions.
I hope this helps. Good luck with your writing.