Adverbs are words that modify verbs, adjectives, other adverbs, and sometimes clauses and whole sentences. Adjectives are words that modify nouns and pronouns. Be careful not to use an adjective where you need an adverb. Consider the following sentences, for instance:
[WRONG] Once the test was over, Sharon walked slow out of the classroom.
[RIGHT] Once the test was over, Sharon walked slowly out of the classroom.
The sentence needs an adverb, not an adjective, to modify the verb "walked."
[WRONG] We tried real hard to get the muffin mixture perfect.
[RIGHT] We tried really hard to get the muffin mixture perfect.
The sentence needs an adverb, not an adjective, to modify the adjective "hard." (Note that "really" is an informal substitute for "very", and you should avoid in in formal essays.)
Using "good," "bad," "well," and "badly."
You might also note the distinctions between "good" and "bad" (which are adjectives) and "well" and "badly" (which are adverbs):
Shelley plays the piano well and the drums badly.
The actor's performance was good even though he felt bad that night.
"Well" is an adjective only when it refers to health or condition:
She protested that she was well enough to start playing sports again.
Using Adjectives with Linking Verbs
In the same vein, remember that adjectives modify nouns and pronouns. Do not mistakenly use an adverb to modify these parts of speech.
For example, after a linking verb you may be tempted to use an adverb instead of an adjective. You will recall that the linking verb is a special kind of verb because it links its subject to a subject complement. A subject complement can be either a noun (renaming the subject) or a modifier (describing the subject). When it is a modifier it must be an adjective because it describes the subject (always a noun or pronoun). It does not modify the linking verb itself and should therefore not be an adverb:
[WRONG] We felt badly about having caused the accident
[RIGHT] We felt bad about having caused the accident.
Using Conjunctive Adverbs
The conjunctive adverb is a special kind of adverb that often serves as a transition between two independent clauses in a sentence. Some common conjunctive adverbs are "therefore," "however," "moreover," "nevertheless," "consequently," and "furthermore." When using a conjunctive adverb at the beginning of the second independent clause, be sure to precede it with a semicolon not a comma.
My roommate usually listens to rock music; however, he also likes John Coltrane and several other jazz musicians.