It is important to know what each of the formats demand.
If you have each of those items in your opening paragraph your reader will know what they are reading, why they are reading it, and what they can expect to get out of it. Organize the essay so that it covers a set list of subtopics that each support your main thesis.
If it's a long essay, you should break it up into sections with headings that focus on specific subtopics.
Summarize complex paragraphs with concise sentences that explain what the paragraph said. Create transitions between paragraphs so that one paragraph follows from the next. When in doubt, break long sentences into smaller sentences.
You are trying to make it all easy to understand for your reader. Avoid sentences that are repetitive and don't provide new information.
Check every one of them and see if you can rewrite it more clearly.
When you use *these* words carelessly, your reader will need to think more to understand what you are referring to.
The more organized your writing, the more clearly you will understand and communicate your own ideas. Throw away weak and empty sentences ("Angioplasty is an important procedure." "Emotions are a central element in people's lives."). You can check for clarity by making sure they read well.
Read them out loud to yourself or have someone else read them out loud to you. Explain novel terms (jargon) when you introduce them. Avoid jargon except where it communicates key concepts.
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Psychology is an extremely interesting subject but a major cause of concern among students is writing those innumerable psychology papers during the course.