Well you want slang maybe? What's up = ti leei (τι λέει) ; many times we just use English though...."hey re" for "hey"....or "pos paei" (πώς παει) for "what's up" again You are beautiful could say "eisai wraios" (είσαι ωραίος ) pronounced (oh-ray-os)....that is for man....for woman say "eisai wraia" (εἰσαι ωραἰα), but mostly we use omorfos (for man again)...so "είσαι ομόρφος" I hope that helps!