How to approach a cute stranger on the street - Making strong eye contact at first and see where it takes you. Nothing more, nothing less.
How to approach your gym/work crush - some subtle hints, maybe a few light touches to the arm, some extra but low key laughs at his semi-decent jokes. Or you can ask him for help in some way, shape, or form. If he's not brain-dead, he will catch on.
How to close the second date - If he is calling, texting, or emailing after a date then it's safe to say he is probably still interested. Don't be afraid to take charge (casually) and ask him what his upcoming week/weekend plans are.
How to ask a guy out online - Be genuine and friendly, and look for something in common to talk about.
How to turn a friendship with a guy into something more - As friends, you should be as open and honest as possible, but don't put too much pressure on the situation. He might not have a clue how you feel.