last time i approached a chick i failed miserably but i still learned something (or rather it's something i already knew but for some reason didn't do at that specific time). basically, you gotta establish eye contact first. try to look at her without looking like a creepy rapist. once eye contact is established, smile slightly to show her you're attracted and see how she reacts, if you can sense she's open for you to approach (she'll smile back or something like that), approach. another good thing is when she breaks eye contact first. then you should approach right away. you've sort of established dominance at that point. when you approach, it doesn't really matter that much what you say. just make a comment about the surroundings or the moment and start a convo no matter how dull. what matters is that she clearly gets your intentions.
see if she's attracted and if you approach, all you have to do is not fukk it up. cause if she's attracted to you, at this point she's only looking for an excuse to spend more time with you and get to know you more. that is, any excuse that won't make her look too much desperate/slutty. and your job is to provide that.
my mistake with the chick i was talking about was that i didn't establish eye contact before approaching. so i basically looked like the guy that came out of nowhere, talking to her. see from her perspective she probably saw it as "this guy has been looking at me for god knows how long and then came up to me out of nowhere like a stalker". doesn't help that i approached from behind, lol.
anyway, my main point is that it doesn't matter how you approach, just establish eye contact and start a regular convo while making it clear you're attracted to her through your body language.
those pick up artist techniques have some pretty good nuggets of info sometimes too. some of it is kinda lame or BS and will have you doing too much but some of it is spot on. but realize you gotta approach while being yourself, not a character. and if being yourself doesn't work cause you're a lame or a bytch ass nikka then change who you are. become a better person and THEN start approaching chicks. that way you're not acting out of character cause it's the new you and it's real.