Ask yourself whether the word you want to classify fits into one of four main types: identifiers, verbs, modifiers, and connectors. Identifiers name people, places and things. Verbs show action and being. Modifiers give extra details. Connectors link words and phrases together. Once you have a sense of which large category your word fits, you are ready to ask more specific questions to determine its part of speech.
Determine the next question that you should ask. If you are working with an identifier ask whether the word names a specific person, place or thing. For example, "dog", "honesty", " New York", or "Dad" are all nouns. If the word identifies a person, place or thing, but is not specific, it is a pronoun. For example, "he", "it", or "them". If the word is a modifier, it can either give details about a noun, as in "blue" or "small", or about a verb, as in "quickly" or "roughly". Noun modifiers are adjectives. Verb modifiers are adverbs. If the word is a connector, it could link two words, phrases, or clauses. For example, "and", "but", and "or". These words are called conjunctions. Other connectors introduce phrases that show possession or location such as: "of", "for", "under" etc. These words are prepositions.
Check your classification by looking up the word in the dictionary. Usually the abbreviation for a word's part of speech is located after the pronunciation guide in a dictionary. If a word can be classified in more than one category, all the options will be defined in turn in the dictionary.