1. Explain it simply
再 means doing something once more, or doing the next thing afterwards.
Put 再 immediately before the verb, never after it and never at the end.
再 is for the future or a suggestion, so use it with plans and requests, not finished past actions.
2. Show examples
你再看看这本书吧。
Nǐ zài kànkan zhè běn shū ba.
Take another look at this book.
再 = again, before the verb
让我想想，再告诉你。
Ràng wǒ xiǎngxiang, zài gàosu nǐ.
Let me think, then I'll tell you.
再 = then / afterwards
我们明天再去吧。
Wǒmen míngtiān zài qù ba.
Let's go again tomorrow.
再 before the verb 去
3. Share a tip
Time words like 明天 or 下午 come before 再, and 再 comes right before the verb: 你明天再来吧。 Because 再 points to the future, don't use it for actions that already happened.