The most common pronoun mistake is pronoun-antecedent agreement, particularly for indefinite pronouns. Here is a list of the indefinite pronouns that are always singular:

• anybody neither
• anyone nobody
• anything no one
• each one
• either somebody
• every someone
• everybody something
• everyone

Example:    Everyone is going to the banquet with his or her date.

Everyone is the indefinite pronoun (and the antecedent), and it is singular. Consequently, the verb that goes with it must be singular, is going. And the pronouns referring to everyone must be singular, his or her.

Some indefinite pronouns can be singular or plural (all, any, more, most, none, some).

Example:   All of the managers go to their favorite restaurant.

The phrase of the managers indicates that all is plural because more than one manager isinvolved; consequently, the pronoun referring to all must be plural, their. Notice that the verb is plural, go.