How are "pretty" and "quite" used?

Pretty and quite belong to a group of adjectives known as 'intensifiers'. These words are often used to create emphasis or indicate exactitude.

These intensifiers actually make your writing less clear.

For example:

• The ball is pretty round.
• The ball is round.

Here, the sentence with the intensifier pretty is less exact than the sentence without it.

In technical writing, you should avoid using intensifiers in your work.

If you're writing fiction, they can be used if your character speaks casually or in an opinionated manner. But even then, don't overdo it!