Identify the nouns, adjectives and verbs within the sentence first. Look at the remainder of the sentence. Determine whether any words modify or describe the verbs you have already identified. As an example, in the sentence "My dog swam quickly," you can initially determine that the word "dog" is a noun and the word "swam" is a verb. The last word, "quickly," describes how the dog swam and is therefore the adverb.
Identify the verb in the sentence. Ask the question, "How was that action performed?" and replace "that action" with the identified verb. As an example, for the sentence "She sang flawlessly," ask yourself how she sang. The answer, "flawlessly," is the adverb in this sentence.
Adverbs can also modify adjectives. Identify the adjectives in the sentence. Determine whether any words describe or modify any of the adjectives. As an example, in the sentence "She is extremely qualified," the word "qualified" describes the woman in the sentence. The word "extremely" describes how qualified the woman is and is therefore the adverb in the sentence.
Adverbs can also modify other adverbs. Identify an adverb that modifies a verb or adjective within a sentence. Look for a word that modifies the identified adverb. As an example, in the sentence "She walked very quickly," the word "quickly" is an adverb that describes the verb "walked." The word "very" describes how the woman walked and is also an adverb.