Decide on your research question. Many researchers start with nothing specific in mind (inductive reasoning) or with a very specific idea in mind (deductive reasoning). You could think about looking for signs of racism, sexism, ageism, homophobia, transphobia, or body shaming, or body positivity. Example –

Past researchers have looked for certain themes (i.e., research questions):

what kind of personal information do people share on twitter?

do people believe election results?

do most commenters have a negative view about being overweight?