There are four main types of context clues that can help guess the meaning of unknown words:
1) Examples - Words used in examples can provide clues to a word's definition.
2) Synonyms - A word with a similar meaning used in the same context provides a clue.
3) Antonyms - Opposite words help define an unknown word's meaning.
4) General sense - When no other clues exist, analyzing the overall sense of the sentence or passage can help guess a word's definition.