Hey Zphix!
My very favorite places are Dept. Stores, Malls, and gatherings like fairs... Though I'm always on the lookout if I need to go to any public place.
- Malls give you the advantage of being able to approach many girls in the same area regardless of whether or not something good happens. The downside is that if you go too often, security will recognize you quickly, and will probably become suspicious. You run the risk of being kicked out.
- Department stores have no mall security, and due to the variety of goods that they sell, you get to meet all kinds of different girls who are there for many different reasons. The downside is that I'd strongly recommend getting out as soon as you get a good interaction that number closes with a girl. It's a smaller place, and she may see you.
- Fairs are my favorite because they are populated, large, and temporary. There are plenty of beautiful girls there that have many reasons to stop in random places, making them very easy to open. They are also far more likely to be with their friends and not with parents, so they have fewer inhibitions. The best part is that you know it won't be around for long, and you can take plenty more risks without worrying about attracting attention and getting kicked out.
The fact that they don't last long is also a downside. Going to a fair or a social gathering isn't something you can do consistently, because they aren't always available. Also, unlike department stores and malls, there's an admission fee, and you can't just choose not to spend money.
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In terms of tactics and techniques, I would say focus more on nonverbals than what you actually say.
- For starters, don't settle for the "okay" girls. Only approach the ones you find genuinely beautiful. They are actually much friendlier. If they are fat or just okay, generally they don't have a whole lot of confidence and they'll think something's up if you try to compliment them. I think each girl can also tell at a subconscious level how genuine you are. If she truly is beautiful, you'll be much more genuine automatically.
- In my experience, just a genuine compliment and a hello is a pretty consistent opener, and you can phrase it just about any way you want.
- Consciously slow down your speech. Slow down your vowel sounds and pause plenty. It not only gives you more time to think, it's just more attractive in general.
- Let her know by your eye contact and body language how you feel about her. You can say all you want, but if you slouch and look down at her feet, you won't get anywhere. A trick I learned is to look at her and get close to her in a way that would seem totally gay and uncomfortable around another guy. Look into her left eye (on your right side), and keep using flirty facial expressions and gestures.
- When you introduce yourself and ask for her name, shake her hand and hold it until either she pulls away, or something happens to make it less convenient to continue holding hands, (such as getting her on a mini date.)
- Find any excuse to move her. This makes her invest in the conversation and shows that you can lead. My favorite thing to do is tell her I don't want to get in the way of other people, but there's a variety of ways this can be done.
- Find any opportunity to get her to invest. Investment is anything that causes her to stop what she's doing and do what you tell her. This can be done by examining her accessories, telling her to hold random things for you, moving her, and getting her to come closer and whisper to you.
- Ideally, number close in the middle of an interaction and continue talking with her afterwards.
- Finally, try to keep the conversation on her. Don't talk about impersonal things. Instead, make it your goal to figure her out as a person. What makes her tick? What inspires her? Who is she?
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For groups of girls, girls with their moms, or girls with their dads, I think you know the drill

Anybody who hasn't seen the post about approaching girls with groups or parents should look at this post viewtopic.php?f=3&t=2368. I can't even articulate how useful it has become.
Hope that helps!