how to write hi in cantonese?

你好
您好

I can't tell you the Cantonese pronunciation, but the Mandarin pronunciation for the first one is "ni3 hao3" (ni actually is pronounced as 2 tone since 3rd tone plus 3rd tone = 2nd tone). The Mandarin pronunciation for the second one is "nin3 hao3" with the same tone rule. The second one is more formal and is used as a greeting for elders, teachers, professionals upon first meeting them, etc.

Even though the pronunciation is different, the characters are the same. That's the beauty of all the dialects in China . . . they are vastly different in how they are spoken, but share the same meanings in writing!

Good luck!

in cantonese: 你好 (lei ho)

你好 = nei5 hou2

Cantonese (China) Néih hóu
Cantonese (China) Neilhou

This is the one my wife would use, she is from Taiwan:
Cantonese (China) Lay ho(pronounced like it looks)

Cantonese (China) Ho yat
Cantonese (China) Ngh on
Cantonese (China) Jou san

These are all different ways to say hello in cantonese

嗨.

Hello, My wife is from China. HI and hello are used the same. It is NI HAO

Randy