using context clues or a dictionary to define unfamiliar words
restating main ideas in my own words
finding a single idea or concept that links the big ideas in each quatrain
Explanation:
In order to be able to identify the central ideas in a sonnet it is important to know all the words that the poem says, so if you don´t know them a dictionary could come handy to help you better understand the meaning of the given words, after that when you have that you can put it in your own words, by doing so you are giving some meaning and understanding the poem, after that you just have to continue to connect main ideas in the text and you get the theme or the central idea in the sonnet.
If you are wondering what you have to do, just tell about your life (but you don't have to tell everything), and tell one time when your view of the world changed, like when everything seemed clearer for you or much more complicated.