Look at word choice. Words have positive, negative and neutral associations, even if they are not being used to describe. Running amuck and running around are the same action, but leave the reader with different images. Pay attention to the connotations of words.
Analyze the phrasing used to describe events. Is the author sarcastic? Do they use many metaphors, or lay out facts without opinion?
Ask yourself how the information is presented. What order do you receive information in? How is the author trying to persuade you, if they are?
Read the latent text. What information is not present? What has been ignored or omitted? This will tell you the author's intention and help to clue you into tone.
Consider how you feel when reading. What emotions come naturally to you? Do you get angry, sad or joyous? Do you feel that the author's trying to persuade you?