Informal:
* "नमस्ते, क्या हाल है?" (Namaste, kya haal hai?) - This is the most common and polite way to say "Hi, how are you?" It is suitable for friends, family, and people you know well.
* "हाय, क्या चल रहा है?" (Hi, kya chal raha hai?) - This is a more casual way to say "Hi, what's up?" and is more suitable for friends and people you are comfortable with.
* "क्या हुआ?" (Kya hua?) - This is a very casual and informal way to say "What's up?" and is only suitable for close friends.
Formal:
* "नमस्ते, आप कैसे हैं?" (Namaste, aap kaise hain?) - This is the formal way to say "Hi, how are you?" and is suitable for elders, strangers, and people you respect.
* "शुभ प्रभात / शुभ दोपहर / शुभ संध्या, आप कैसे हैं?" (Shubh prabhat / Shubh dopahar / Shubh sandhya, aap kaise hain?) - This is a more formal greeting that incorporates the time of day and is suitable for most situations.
It's important to note that:
* "Namaste" is a respectful greeting and is generally used instead of "hello" in Hindi.
* "Kya haal hai?" and "aap kaise hain?" are both ways of asking "how are you?" but the former is more informal than the latter.
* The choice of which greeting to use depends on the situation and the person you are speaking to.
You can also combine different phrases to create a more natural-sounding greeting:
* "नमस्ते, क्या हाल है? सब ठीक है?" (Namaste, kya haal hai? Sab theek hai?) - "Hi, how are you? Everything okay?"
* "हाय, क्या चल रहा है? कैसे हो?" (Hi, kya chal raha hai? Kaise ho?) - "Hi, what's up? How are you?"
Remember that pronunciation is important in Hindi. You can find online resources and audio recordings to help you practice your pronunciation.