Frequency of actions is expressed by frequency adverbs and adverbial phrases.
Words describing frequency of actions (frequency adverbs)
always, constantly, frequently, usually, often, sometimes, rarely, never
Phrases describing frequency of actions (adverbial frequency phrases)
from time to time, every second, every minute, every day etc
Words describing marginal frequencies of actions
Marginal frequencies of actions: at maximum or minimum
always, never, constantly, at all times, all the time
to work on:
Visual table of frequencies
Position of such words in the sentence
Examples
Never / ever usage
Double negative
More on Introduction to Tenses: