Here are a few options for an informal opening greeting in Engpsh:
"Hi, how's it going?"
"Hey, what's up?"
"Hello, how are you doing?"
"Good morning/afternoon/evening, how are you?"
Keep in mind that the tone and formapty of the greeting may vary depending on the context and the relationship between the speakers. It's always a good idea to pay attention to cultural norms and social cues when communicating in a different language.