Casual:
* Alright? (Very common, can be used as both a greeting and a question about someone's well-being)
* How's it going? (Another very common greeting, particularly amongst younger people)
* What's up? (Borrowed from American slang, becoming increasingly popular)
* Hiya! (Short for "How do you do?")
* Right then! (More informal and friendly, often used with a slight upward inflection)
More regional:
* Alright, mate? (Common in London and the South East, "mate" is a friendly term for a man)
* Alright, love? (Also common in London and the South East, "love" is a friendly term for a woman or anyone)
* How do you do? (More formal, often used ironically or humorously)
* Cheers! (Often used as a general greeting, but can also mean "thank you")
* Morning! (Common greeting in the morning)
* Afternoon! (Common greeting in the afternoon)
* Good evening! (Common greeting in the evening)
Remember:
* Context matters! The appropriate greeting depends on the situation, the person you're talking to, and your level of familiarity.
* Regional variations! Slang varies greatly depending on the region of England.
Enjoy using these greetings and see how they are received!