Picking something from their profile to ask them about is the usual way. If they have a dog picture talk about the dog type of thing. Entertaining them with questions about random topics seems to work too. Like the first message could be something weird, along the lines of "if you were turned into a fruit by a wizard, what fruit would you want to be and why?".
I don't like any specific pick-up lines, because I don't like seeing dating as a game. I think it dehumanizes the process. Still, I agree saying "hey" isn't interesting. Thus, I usually do what Destin suggested: Look at their profile and comment on something you found interesting. Think to yourself: After all, why did you start chatting with that person? What grabbed your attention? If you were talking in person, you wouldn't say "hey" and stare at the person. So, imagine you were talking in person: What would you say?
My pick up lines hardly ever get replies, so I won't tell you what they are. I kind of like to keep it polite and friendly at first, then I might get a bit saucy later on in the chat if I've managed to hold their attention long enough. But one greeting I am sick of receiving is "hey, how's you?" HATE IT. That's the sort of thing my alcoholic customers say to me when they come into the shop to buy their 4th bottle of whiskey on the same afternoon. At least say "How are you?" or "How's it going?" How's you is just.... Ugh.
I agree with what has been said above. Try finding something on their profile you found interesting or relatable, and ask them about it. When writing the first message, say something that you don't think they've heard before. Instead of the typical "hey", or cliche response, comment on a picture, or something that caught your interest on their profile.
Well, I like to be a funny guy so if I want to be cheesy I say something like. “Nice profile pic, did you windex those pants? I can totally see myself in them!” But usually I say hello, and ask them how they are doing.. as I would meeting them in real life.
I usually just tell them their beautiful, cute or comment on one particular picture that I liked. Has served me well so far.
I really suggest thinking of interesting questions that they likely wouldn't have heard before. Sometimes there are things in a person's profile that can automatically get your attention. If the two of you are massive fans of a show, or have really passionate political views that mesh together, or share a hobby, then you could always start off like that. But sometimes you find someone and you don't necessarily see any similarities right off the bat, but you still want to get to know them to see. In which case, I always think of questions. I prefer ones that--if they answer truthfully--will allow me to know more about them. "What would make you incredibly happy?" "What is your dream for the future?" "In what ways do you express yourself?" And so on and so forth.
