Separate facts from opinions. For example, during Michelle Obama’s speech at the Democratic National Convention, she mentioned that the White House was built by slaves. Some media outlets reported that this wasn’t true. The website politfact.com investigated Michelle Obama’s statement. Read in this article why Mrs. Obama is right.
Compare multiple media sources.
Language is important. Pay attention to the language the reporter uses. Think about how terms like Crooked Hillary and Dump Trump influence the debate.
Investigate the owners (and editors in chief) of the media outlets. Do they vote? And for which candidate? What government rules and regulations benefit the owner of the media outlet? Do they have a ‘relationship’ with people from a political party? etc.
Realize that different techniques are used to get your attention and that the stories are carefully crafted. Some media outlets purposely show parts of a political event to sell a story. For instance, some media will only show empty seats to confirm that the candidate/speaker is not popular. Other media might focus (more) on angry protesters to paint a certain picture of the candidate’s following.