The dynamics are more complicated when approaching a set. Their disposition of you can vary wildly, on the other hand, you have some control over what they think of you. But in a bar or nightclub, the odds are pretty much stacked against you. There's no amount of indirect, direct, or game magic that's going to make you success rate of hooking any higher.
What really matters is everything you do before you even step in the bar or club. Who do you know? Does the doorman high five you on the way in? Are you fist bumping the bartender? Did the waitress pat you on the ass as you said hello? Are you coming in with a group of people and they're having a good time? Are you the ring leader of that group? Do you have style that sets you apart from everyone else in the room? What are your interactions like with other people in the bar? Are you atleast getting a nod? Regardless how well you do with a set, do the girls at least give you a reaction that at least acknowledges you? How are the rest of the people in the room perceiving the interaction? Do you look happy and confident like you just won the lottery?
The words you say, the pose you make, and the timing of your corny, adorable jokes about your niece are only a mere fraction into your game.
However, there are some things you can do to increase your success to hook the set on your approach:
Always go for the bigger sets. I'm not talking a table for 4 or 5. I'm talking bachorlette party 0f 10+ in a circle in the middle of the bar having a great time. Those are always the best sets to approach because these chicks know it takes balls to approach them when they're in numbers. And even if you bomb it, the rest of the room will think you know them.
Never approach directly to the group or behind their back. It's startling and creepy when you face them. Instead try to approach with your head turn and as if you're trying to get away from them. Distance == comfort with strangers.
If you managed to get their attention, always create a barrier between you and your target with a male member or ugly chick of the group. Again this creates more comfort and they won't be as defensive since you're creating a "gatekeeper" between you and her. Even situating yourself between a physical barrier will still create comfort because you create the illusion that she has more escape routes.
And more importantly smile. I'm not talking a strained smile. I'm talking about the goofy ass grins you get when your buddy farts and tells a **** joke at the same time.