Here are some more appropriate ways to say hello to a cute boy in French, depending on the situation:
Formal:
* Bonjour, monsieur. (Good morning/afternoon/evening, sir) - This is the most polite and respectful way to greet a boy you don't know well.
* Bonjour, jeune homme. (Good morning/afternoon/evening, young man) - This is a slightly more informal way to greet a young boy.
Informal:
* Salut! (Hi!) - This is a casual greeting that's appropriate for friends or someone you know well.
* Coucou! (Hi there! / Hey!) - This is a very informal and friendly greeting, like "Hey!" in English.
If you want to be slightly flirty:
* Salut, tu es mignon! (Hi, you're cute!) - This is a direct way to compliment him but make sure you know him well enough to be flirtatious.
* Bonjour, tu es très beau. (Good morning/afternoon/evening, you are very handsome) - This is a more formal way to compliment him.
Remember: It's important to consider the context and your relationship with the boy before using any of these greetings. It's always best to err on the side of caution and use a more formal greeting if you're unsure.