1. Prepositional Phrases between the subject and the verb do not usually affect the agreement
  - The colors of a rainbow are beautiful.
2. If 2 subjects are joined by and they typically require a plural verb form
  -The cow and the pig are jumping over the moon.
3. If one of the words each, every, or no comes before the subject, the verb is singular
  - No smoking or drinking is allowed. Each man or woman is required to check in

Hope this answer helps :D