I feel the need to say a few words, since I am an active cold approacher myself, and I can see how great this thing could be, yet some of you talk against it.
The main thing for many guys is to conquer their fear of talking to a unknown woman that they find attractive. It took me years to get over it. But then, when I finally started taking real action, I became so much more confident and free. It's like you grow wings.
This act of going in, starting a conversation, and being honest about your intent, I believe, is the right thing to do. It's natural, "manly", feels good, spikes up your dopamine, adrenaline, testosterone, mood, etc.
So one of the main goals of cold approaching is to be able to go up to a woman and know how to start a conversation without being a creep or weirdo about it.
If done right, this usually makes the day for the woman, she feels great and flattered about it, and for you - actually it can change your life, since you are able to meet any women at any place.
Not to mention that these type of social skills transfer to other fields, and can also help you network and meet important people (especially if you are introverted by nature, which I believe most of the cold approachers actually are).
Of course there is a dark side to this game. Your ego gets crushed - well, this is actually a good thing, and needed for any real personal growth. You can suck at it, and feel worthless. Most guys probably try it out for a little bit, and then give up after a few rejections.
But besides that, when you understand the power that this skill has, and the amazing opportunities and life moments that it can create, I think there is something very beautiful about it.
And about the main question of this thread - "How should it look?" - well, you find what works for you. Check out Sasha Daygame, check out RSD Tyler's stuff, check out The London Daygame Model (Tom Torero, Nick Krauser), check out TheNaturalLifestyles (although James' game recently has been very weak from what I saw on the videos). All of these guys have infields on the internet.
Go out and try stuff. Find your way. Or just go and say "hello, I thought you look nice, so I came to meet you". Simple as that. Deliver it without rushing your words, by keeping your eye contact, and having a slight smirk / smiling with your eyes. This can do wonders, if the energy (vibe) behind it is right, and you look well-kept.