If you have balls to open conversations on the bus and other places you don't need to have a problem on the street. The easiest way to do it is to ask a question like where is X or Y. (If she's going towards this direction then awesome - you can walk with her...)
Use all the eye contacts, little smiles, voice tones etc. and BE CHARMING just asking the question. Once she sees that you're pretty hot and manly, she's there already, standing with you. All this in 5 seconds. From there start the pickup. Say something funny (think of something in advance and use it all the time in these situations) and you're in!
By the way, try not to surprise them when you're coming from the front. They need to feel that you're going to stop them for a question.
About coming from the back... I'm not sure. Street game is not my specialty...
Good luck man!
_________________
Train your boxing and raise your SELF-CONFIDENCE with Virtual Boxer - A super effective 3-speed
boxing training game / simulator.
Try the FREEBIES, they're a lot of fun!
