How are you?
How’s it going?
How’s it been?
How is everything?
How’s everything?
How have you been?
How’ve you been?
How you been? (informal)
How’s tricks? (informal)
What have you been up to?
What’s new? (informal)
What’s up? (informal)
Wusup?/Wassup? (slang)
What’s happening? (slang)
Wthat’s going on? (slang)