I don’t know what to start from.
Will your daughter start any extracurriculars when she reaches fourth grade?
You need to mix all the ingredients together before you can start transferring the batter to the pans.
This word consists of kanji with hiragana attached. Because the hiragana ends with an う sound, you know this word is a verb. The kanji itself means start, so the verb version is to start something.
This is a transitive verb. That means it takes a direct object. You start something. Like studying! You should have started studying earlier though, huh?
Since this word has okurigana (hiragana attached to the kanji) you know that it's probably going to be the kun'yomi reading, which you didn't learn with the kanji. Here's a mnemonic to help you:
Right now it's time to begin Haj (はじ). (Haj is the fifth pillar of Islam, and is a pilgrimage to Mecca during the month of Dhu al-Hijja). You need to start Haj right now!