Every time you change topics, start a new paragraph. The first sentence of each paragraph should be a topic sentence that clearly and specifically states the topic. The rest of the sentences should support that topic by giving explanations, premises, descriptions, or examples.
Point of view refers to who is narrating and how. For example, I might choose to use first person narration because it is more casual and personal, as in writing a letter. You should use second person to give instructions; third person (he, she, or they) tells a story or describes an event, usually from an outside and all-knowing narrator.
The first word of each sentence in a paragraph should vary. This technique will help hold the reader's attention and keep you from sounding monotonous. If you are having trouble, think about how you can reword the sentence, or add transitional phrases.
Transitions are words and phrases that clearly signal how ideas are linked. For example, "and" simply presents two or more facts, while the more formal "thus" shows a logical deduction. Other examples are "although," "and so," "nevertheless," "furthermore," "however," and "then."
Active voice is showing who did what, and how--as opposed to showing what was done--so as to convey the most information possible. For example, the sentence "They ate dinner" (active voice) is clearer and more interesting to the reader than its passive, and therefore vague, counterpart, "Dinner was eaten."
Similes describe a relationship between two things, such as, "My fingers felt like ice" or "The house was as cold as the Arctic." The words "like" and "as" are often used in similes to transfer qualities of a known image (here, ice; and the Arctic) to an unknown image (my fingers; the house). Metaphors also describe a the relationship between two things, but are more powerful because they do not compare; they simply equate. For example, "My house was the Arctic."