I usually go with either:
'Hey, just quickly I need to ask you a question on something
I need a females opinion'
followed with a copy and pasted opener, usually shady friend.
60-70(ish)% response rate.
or
'Hey, I need to ask. Are you shy or something?
It's just I've been online for ages and you haven't said hello yet'
only if they are online at that moment though
this probably has more of a 50-60% reply rate.
Be prepared for bitch shields though, 1 response I had was:
"shy my asre.. I chat to who I want to..if I havnt said hallo its because I dont want to"
my reply: 'Wow I love a fiery woman

I thought I was being cute and funny but I must just be being cute.'
got a 'lol shutup' in response, but it led into a conversation.