Picking women up off the street is you see a woman walking on the sidewalk and maybe you pull up next to her in your ride and holla at her or you're walking around in the mall and you go up to her and just start hollaring at her. Or you're at a gas station and you just hollar at the girl and it's your first time seeing her. This is in context of something long-term. There is plenty of one nighter type material doing that, but I personally would avoid attempting anything more than a woman you've met in that manner.
One rule I hold in my mind is that my looks and my game is not unprecedented. I'm not doing something that hasn't been done before and I'm not the only good looking guy out there. If I can just up and approach a woman who has never met me, knows nothing about me and is just comfortable enough to move and groove with me, that raises up red flags in my mind. The only thing she knew about me was she felt how I looked and maybe she enjoyed a minor conversation with me. How many other guys that she thinks looks good and have a little bit of conversation can do the exact same thing?
From my observations, the best women usually are the sort of out of way gems that don't go out much, but you meet them through mutual friends or maybe at some sort of place you frequent and the two of you may not immediately hit it off but eventually grow comfortable with each other.
Can meeting a woman that you street approached work and you end up with a quality woman? Yeah, it can, but I wouldn't say that is a high probability way of doing things.