One best ways to use the common character 的(de) is to have it spice up your nouns with adjectives.

Structure with the noun:
A very common way to modify nouns is to attach an adjective to them using 的 (de).

This structure comes up extremely frequently and is an easy way to attribute features to nouns. Note that if the adjective has two characters (e.g. 漂亮 or 高兴), the 的 is generally required.

Examples:

Piàoliɑnɡ de yīfu.
漂亮 的 衣服。
beautiful clothes

Structure Without the noun：
In some cases, it is possible to drop the noun altogether, and just use the adjective + "的". For this to work, there already has to be context, so that the listener can understand what it is referring to. This construction can mean "one," as in "the blue one", or as something like "mine" or "Sarah's" if the noun that precedes it possesses the noun that is being dropped.

Examples：

A: Nǐ xǐhuɑn shénme nǚháizi? B: Piàoliɑnɡ de.
A:你 喜欢 什么 女孩子？B:漂亮的。
A: What kind of girls do you like? B: Pretty ones.