I stay very aggressive. If the defender is in front of me on a fast break and almost waiting for me, I square him up immediately (so it looks like I running right toward him). Squaring him up puts the ball in my court, so to speak. He stays stationary because I'm coming to him then I'm in control of when I make the next move and to where. That next move could be a simple sidestep, a Euro, or a straight attack if the defender is deep enough and vulnerable enough.
Really, if one defender's back and he's waiting, he's very very vulnerable. His only out is to take a charge or make a spectacular defensive play. I think it's important to keep that in mind when attacking offensively. The defender is the one with the problem, not you.
When a defender is running alongside me, more times than not I just try to attack strong. I suggest working through ways to subtly use your body as a weapon. Strategic bumps and clears at the right time (as you attack) alongside a proper gather and leap, can often be enough to get that defender's body weight moving just enough in the wrong direction to allow for a high level shot attempt.
Worth noting - in most of these situations, I'm doing whatever I can do to score. Many times, this means attacking with my strong hand regardless of where I'm at. My feeling is, I explode twice as well off my strong leg, so trying to be fundamental just for the sake of being fundamental won't always do the trick. It's survival mode at that point. Do what it takes to put the ball in the hole.
My favorite move to use on fast breaks with a single defender looking to get an angle on me though? I've honestly used this a ton
over my career. I feel it should be a lot more common than it is. It gets a fun response because it looks neat, but it's a pretty straight forward maneuver: http://www.youtube.com/watch?v=7D3Qfcl2HbQ
On my list of what NOT to do, I'd say never attack with the priority being to draw a foul. The minute a player tries to draw a foul first and worry about making the shot second, it's usually not going to work out in their favor. For one, it takes one's concentration away from what's most important (making the shot) and two, referees don't respect it. The few times I ref, I'm terrible, but if there's one call I know to let go, it's the one where an offensive player is going out of his way to look for contact.