Often you can guess the meaning of a word from the other words around it. E.g.: ... many people believe that there is only one god but others pay homage to multiple deities. It is obvious that deities is equivalent to gods.
Check the part of speech of a word
Knowing whether the word is a noun (singular or plural), a verb, an adjective or an adverb can help you decide on its meaning within the context. E.g.: What are your thoughts when you see an elderly woman wearing a hijab, a Jewish boy with a yarmulke, or a young black man in a colorful dashiki? You can guess that these nouns denote nationally/religiously identifying articles of clothing.
Also, you may already know one form of the word (e.g. the noun contamination) but not the others (e.g. the noun enculturation, the noun culture, or the verb to enculturate), so you should look closely at the root word to give you a clue.
Use your previous knowledge of English
You may have seen the word in a different context. You can use your previous knowledge and the new context to work out the meaning. Or you may know the separate parts of a word, but may be unfamiliar with the word as a whole. You can use this knowledge to help you work out the meaning.
Check if there is a definition
Sometimes there will be a definition, explanation or example of a vaguely understood word, e.g., Diffusion, or cultural borrowing. These can be introduced by a variety of words – is, means, refers to, in other words, and i.e..