i agree with him ^
the thing about facebook chat or any kind of instant message is you can think about things before you answer. giving you a little more time to really say the right thing.
the thing is you need to analyze the situation and realize what kind of existing relationship you already have with said person.
90% of people you add/add you on facebook you already know.
heres a few examples:
1. ex gf that you havent talked to in a while that youd like to hookup with again: "hey, i know this is kind of out of the blue...but i head a song the other day and it made me think of you." etc.
2. a girl who you kinda know through another friend that you met at a party who added you: "so when are we partying again!?

"
3. a girl youve never met before: "im sorry...but do i know you? i think you mightve randomly added me but im not sure"
4. or a few general first lines: "wow your status is (add adjective). sorry i just had to say it lol"
"hey can i ask you something real quick? your like the only one online"
"i hate the new facebook...i cant find anything! fuck tom or whoever made this up lol"
or the most general of all.... "hey whats up?"
im actually comprising a "how to" about facebook game and instant messaging game in general. so look out for it.
hope i answered your question.
and good luck.
-GL