You can add emphasis to your writing by using strong language. Not the kind of strong language that Parental Adversories warn against; the kind of strong language that using strong verbs, adjectives, and adverbs will produce. The more specific a word is, the more information that word will be able to convey, and the more information that word conveys, the stronger it is.
Lets look at a quick example: Think of the word "monkey." Now, there's really no way to tell what you or I might think of when we hear the word "monkey." If I ask you to think of the word "orangutan," the picture you and I think of will be similar to each other because the word is much more specific. The word "orangutan" is a strong word because it conveys color, size, and shape without having to describe each characteristic specifically. If the purpose of most writing is to communicate a message to an audience, it is a good idea to be specific so that you can avoid any confusion.
Specific or strong verbs act as though they are a verb and an adverb all in one: giving a description of the action and how the action was completed (or in what manner the action was completed). Let's look at a couple examples of weak versus strong verbs:
Some words do not have a more specific counterpart to help create stronger writing. For example, a countertop is a countertop. To be anything more specific than a countertop, it will need an adjective or two to make it a specific countertop: the marble countertop, the chipped countertop, the laminate countertop, etc. Adjectives can add emphasis by turning a regular noun into a specific noun by telling the reader "what kind" of noun it is. [It is a BLUE car.]
Adverbs provide the same service for verbs, other adverbs, and adjectives, by telling the reader "how" an action took place: After he saw her standing by the bus, he clumsily dropped his books and sprinted off down the street. He was so distracted he unknowingly took four lefts and ended up back at the bus stop. He gathered his books and anxiously sat on the bench just outside her peripheral vision.
To add emphasis to the main ideas in your writing, you'll need to replace adverb + verb combinations with strong verbs, and replace any adjective + noun combinations with strong nouns in those sentences. When it comes to the main ideas of an essay, it is important to be as clear and concise as possible, and the best way to do that is by removing any clutter-words from those sentences: let those strong nouns and verbs do the heavy lifting!
For all other areas of your paper, use adjectives and adverbs sparingly, only when they can make a noun or verb stronger or more specific. Being selective about when and where you use adjectives and adverbs will help emphasize the places where they are used.