I tried the eyebrows and smiles one time but the person I was communicating to non-verbally did not see my facial expressions due to poor eye site and thought I was both embarrassing them and ignoring them. Now I express my "hi"s verbally or with an arm wave.
I'm bout to confuse you all because I say hi differently depending on who I'm saying it to and how I see them, so pay attention: When walking past them: Friends - Lift eyebrows and nod head up Complete strangers - nod head down an small smile Teachers (those I like) - Wave an say it loud Family - Same as teachers.
When actually walking to them: Friends - Walk up and say sup Complete strangers - Generally same as walking past them Teachers - Say hi an maybe talk Family - Depends on relative, generally I say hey
With females I'm crushing on/flirting with: I usually lift my eyebrows, an was told I do a cute eye thing like squinting but not exactly...