Look for run-on sentences. Technically there are two types of run-ons: fused sentences and comma splices A fused sentence is created when two independent clauses are "fused" together without any punctuation between them, for example: "Tom walked into the conference room he was nervous about giving the speech." A comma splice, on the other hand, is created when two independent clauses are linked with only a comma, for example: "Tom walked into the conference room, he was nervous about giving the speech."
Locate subject-verb disagreement errors. Subject-verb disagreement errors most often occur when people are writing in the present tense. In order to recognize and correct this error, remember that verbs must agree with their subjects in number (singular or plural) and in person (third, second or third).
Moreover, according to Diana Hacker, author of "The Bedford Book for Writers," it's important to make certain that the verb is actually agreeing with its subject, not with a word that comes between, as in this example: "The tulips in the pot on the balcony needs watering." "Balcony" is singular, but the subject is "tulips," so the correct verb is "need."
Remove errors in verb tense. The most common error in verb tense occurs when a writer switches tense within a sentence, for instance: "After Tom arrived at the park, he runs two laps around the track." ("Arrived" is past tense, but "runs" is present tense.)
Revise errors in mood. There are three moods in the English language: indicative, imperative and subjunctive. Only the subjunctive mood, though, seems to create problems for people. Subjunctive mood should be used whenever you're expressing a wish, request or condition contrary to fact. For example,
1. I wish my husband were more organized. (Not was)
2. I asked that he consider my proposal. (Not considers or considered)
3. If I were you, I would probably make the same stupid mistake. (Not was)
Correct errors in voice. When a sentence is in passive voice, what should be the subject becomes the object of a preposition, which weakens the impact of the sentence. Moreover, active voice is more direct, simpler, and less word; for example, compare the following sentences:
1. Tom's new novel was released by the publisher in May. (Passive)
2. The publisher released Tom's new novel in May. (Active)
Remove pronoun and antecedent disagreement errors. Since pronouns take the place of nouns, they should agree in person and number with their antecedents (the nouns they replace). Therefore, do not use singular pronouns to refer to plural nouns, or vice versa. For example, do not write or say something like this: "When someone has been drinking, they should not drive." Instead, write or say, "When someone has been drinking, he or she should not drive."
Correct errors in pronoun case. There are three pronoun cases: subjective, objective, possessive. The subjective case pronouns include "I, you, he, she, it, we, they, whoever, etc; and they function either as subjects of verbs or as subject complements, for example: "He is going to the movies;" or "The man on the corner was he."
Objective case pronouns include "me, you, him, her, it," etc; and they function as direct objects, indirect objects or objects of preposition, for example: "Tom's mother sent him a gift;" or "She sent a gift to him."
Possessive case pronouns naturally show ownership and include "my, your, his, hers, its, our, their, whose, etc, for example: "That new red Corvette is his;" or "My new car is a red Corvette."
Note: Always use possessive case pronouns before gerunds or gerund phrases (a gerund is an "ing" verb that is functioning as a noun), for example: "Sue told Tom that his snoring was keeping her awake."
Remove split infinitives. An infinitive consists of the word "to" plus a verb, for example: to try, to be, to give, etc. Split infinitives occur whenever you put a word between the two components of the infinitive, for example: "Tom is going to probably try out for the play." In order to correct a split infinitive, reword the sentence: "Tom is probably going to try out for the play."
Step 1: Correct sentence fragments. In order to be classified as a sentence, a group of words must express a complete thought. A fragment, however, while also a group of words, does not express a complete thought.
Some fragments lack a subject or a verb or both, for example: "Walking into the conference room." Other fragments might contain a subject and a verb, but they begin with a subordinating conjunction like "after," 'although" or "when;" and since they begin with a subordinating conjunction, these word groups are "subordinate" and, therefore, cannot stand alone as sentences; for example: "When Tom looked at the audience."
In order to correct fragments, William H. Barnwell and Robert Dees, coauthors of "The Resourceful Writer," say that writers should ask these two questions:
1. If someone wrote the statement on a note to you, with nothing else in the note, would it make sense?
2. Does the statement contain a subject (at least an understood subject, for example, "you") and a verb?