Biomega said:
Oh... pitfalls. 'Harshly' is a tone, right? Then, how to describe a manner of speech?
"Harshly" can be used in both ways: "Spoke harshly" or "Spoke in a harsh tone".
Describing manner of speech? Usually it coincides with the emotions of the speaker. If he's happy, he speaks happily. If he's sad, he speaks sadly. That's good for a start. If you want to skip that step and go straight to advanced adjectives like "nonchalantly" (implying apathy or indifference) or "incredulously" (implying disbelief or skepticism), then you'll have to go find more advanced synonyms of the character's emotions, or delve further into the exact emotion. For example, when a character is sad, he can be mournful, despairing, melancholic, and so forth.
To avoid sounding repetitive in describing speech, you can drop the adjective altogether, instead using a description of another part of the character's body to imply the tone of his speech. For example, if you want to show that a character is angry, instead of writing "he said angrily", you can write "he said, his eyes burning with anger".
Alternatively, you can substitute "said". If the character is making a retaliatory speech, write "he shot back". The possibilities are endless.