Should Gerund or Infinitive?

Gerunds and infinitives can replace a noun in a sentence. Gerund = the present participle (-ing) form of the verb, e.g., singing, dancing, running. Infinitive = to + the base form of the verb, e.g., to sing, to dance, to run. Whether you use a gerund or an infinitive depends on the main verb in the sentence.

Is should a gerund?

There is no gerund after "should".

How do you know if a verb is followed by a gerund or infinitive?

Tip Number 1: you almost always find a gerund after a preposition. For example, “She is afraid of flying.” In this sentence “of” is the preposition and “flying” is the gerund. You cannot say “She is afraid of to fly.” An infinitive cannot be the object of a preposition, only a gerund can.