''How can I correctly use verbs which follow prepositions?'' Is this your question? Verbs usually don't change when they sit before a preposition (I mean, they don't change because of the preposition if the preposition follows). If a verb follows a preposition, it's usually in gerund form (+ing), which also means it now functions as a noun. Specifically, ''an action as a noun''. Of course, ''to'' is usually followed by the infinitive (unchanged) form of the verb, despite a couple of exceptions.