Hong Kong and standard Cantonese have some pronunciation differences.
Chinese has several phrases you can use to say "Hello." While there is no one general word that functions as a one-to-one translation with English, certain phrases are used in certain circumstances as the equivalent. These range from neutral to informal, with telephone greetings getting their own version. Two Chinese languages, Mandarin and Cantonese, have some related terms.
Instructions
Mandarin
1. Use "ni hao" as a basic hello greeting. This literally means "you fine," and is like saying "Hello, how are you?" The word "ni" usually uses the third tone, which rises from low to high, but in this phrase, the tone undergoes something called tone sandhi, meaning it changes when the word following it has a third tone as well. "Hao" uses the third tone, so the tone on "ni" changes to a high rising tone--it doesn't start off quite as low.
2. Add "a" or "ma" with no tone to the end to change the phrase into the equivalent of "how do you do" or "nice to meet you" when you meet someone for the first time.
3. Say hello when answering the telephone by using "wei." Pronounce this similar to English "way" and use the fourth tone, falling. This can also mean "Hey."
Cantonese
4. Use "neih hou" or "leih hou" for the basic greeting. This is the Cantonese equivalent of "ni hao." "Leih hou" is Hong Kong dialect; one of the distinguishing features of Hong Kong Cantonese is that word-initial "n" has changed to "l," so "neih" becomes "leih." Say "neih/leih" with a low rising tone. Keith S.T. Tong and Gregory James write in "Colloquial Cantonese" that this tone is "like asking a question, but rather suspiciously."
The "ei" is pronounced like the -ey in "hey." Use a high rising tone for "hou." As with Mandarin "ni hao," add "a" or "ma" at the end for "How do you do." However, these have a mid level tone in Cantonese.
5. Use "wai" when answering the telephone. This is similar in pronunciation to English "why" and uses a high rising tone. If you change the tone to a mid level tone, the meaning changes to "Hey!"
6. Say "Jeuigahn dim a?" to mean hello in the sense of "How've you been," note Stephen Matthews and Virginia Yip in "Cantonese: A Comprehensive Grammar." This is very informal; use it with friends you know well.
Both "jeui" and "a" take mid level tones; "dim" uses high rising"; and "gahn" uses a low level tone. Pronounce "jeui" like "joy," but make the "eui" a central, somewhat rounded vowel. Say "oy," and as you make the sound, gradually move it toward the center in your mouth, keeping your lips somewhat rounded. Note that this is not nearly as tense a vowel as that represented by the "o" with an umlaut in German. "Eui" is rather relaxed.