Frequency adverbs are added to indicate how often something is done. Examples of frequency adverbs are まいにち (everyday), よく(often), and ときどき (sometimes.)
わたしはときどききっさてんにいきます。 I sometimes go to a coffee shop.
It is also important to remember that adverbs of infrequency must be followed by a negative at the end of the sentence.
わたしはぜんぜんテレビをみます。 I do not watch TV at all.