Simply say Hi or ask for chat..

anyone have good answer ??

Pull her pigtails.

Or dip one in the inkwell and tap her on the shoulder?

Neither.
Both are too common to get you noticed.

Also, do not tell them how good they look, makes
one seem interested in only looks.

And don't call them 'dear' it screams scammer.

And never say how great their profile is especially
if you have not read it.

Be sincere, even if it feels clumsy.

If all else fails, I would go with the pigtail
pulling ;-)

I usually smash my ice cream in their face