Find the infinitive form of a verb, which is always at the beginning of an infinitive phrase. The infinitive is always made up of the word "to" followed by the non-conjugated form of the verb. For example, the infinitive form of the verb "write" is "to write."
Find and, if possible, label all the nouns that come after the infinitive form in the sentence.
Determine the grammatical function of the nouns in question --- whether they are subjects (nouns doing the action of a verb) or objects (nouns receiving the action of a verb). If a noun is in a participle phrase, do not label it now --- we will return to it later. Each noun should now be tied to some form of a verb (this includes the infinitive, though it is technically not a verb). Draw a line from each noun to the verb to which it is related.
Identify all the modifiers --- adjectives or adverbs --- in the sentence that come after the infinitive, including the participle phrases mentioned above, which also act as modifiers. As you did with the nouns, draw a line from all modifiers to the nouns or verbs they modify, including the infinitive.
Examine all the words you have labelled so far. All the nouns that are the objects of the infinitive and any modifiers affecting either those objects or the infinitive itself are the infinitive phrase. Draw a circle around the infinitive phrase. You will now be able to identify the end as the last word in the circled phrase.