While it is generally very easy to match singular subjects to singular verbs, things can get complicated sometimes. For example when nouns are compounded, the verb should become plural.
John is going out today.
Mary is going out today.
John and Mary are going out day.
Since we have a compound subject, two nouns/pronouns joined together by a conjunction, the verb should be plural ,since now the subject consist of more than one element.
Some more examples:
Smith and Wesson are out on a date.
Edward looks great today.
Edward and Matthew look great today.
Adrian and Andrew are watching the crowds at the cinema hall.
Examples of compound subjects made up of a noun and a pronoun.
She and John Smith are out on a date.
She and the President of the USA, are close friends.
Examples of compound subjects made up of two pronouns:
He and his friends are out on a vacation.
She and her entourage are nowhere to be seen.
However, do understand that when the nouns are combined using phrases such as in addition to, together, together with, along with, as well as, they should be treated as singular. These phrases are called as additives.
Smith, along with Wesson is out on a date.
Adrian, together with Andrew is watching the crowds at the cinema hall.
John, as well as his father, is going out today.
John and his father are going out today. (because of the compounding effect of and)