The correct spelling of this word is "I'm wasteful." It is a contraction of the phrase "I am wasteful" and is pronounced /aɪm ˈweɪstfəl/. The IPA phonetic transcription shows that the sound "ai" corresponds to the letter combination "I'm," and the stress falls on the first syllable of "wasteful." Spelling errors can lead to miscommunication and misunderstandings, which is why it is crucial to pay attention to the correct spelling and pronunciation of words.