Subject-verb agreement is a basic rule in writing English. Even so, many writers get it wrong, especially if there is anything between the subject and the verb. Singular subjects take singular verbs; plural subjects take plural verbs.

Misplaced modifiers create confusion as to who is doing what: “Lying in the sand, the waves washed over me.”

The solution: Ensure that the words being modified are next to the modifiers: “The waves washed over me while I was lying in the sand.”