I found some good rule of thumb for setting up a cam;
Advancing the cam gear opens a valve earlier, and closes it sooner... retarding the cam gear, opens the valve later, and closes it later... since all you've done is moved a fixed event.
Advancing Intake and Exhaust : This will provide the car with more bottom end power, and will decrease top end. Advancing both cam gears will move overlap earlier.
Retarding Intake and Exhaust : This will increase the cars top end, but will decrease low end. Retarding both cam gears will move the overlap later and but will not change the amount of overlap.
Advance Exhaust Only : This will help the cars top end, and it reduces overlap.
Retard Exhaust only : This will help the cars mid range power, very useful for cars with big turbos / big cams. By increasing overlap, It decreases lag significantly. Doing this will bring the boost on all at once.
Advance Intake only : This will increase overlap and helps the cars bottom end and mid range power. This mod will bring the turbo on all at once.
The lift has a dramatic effect on low R.P.M. performance, but has a lesser effect at higher R.P.M.s.
Duration has the opposite effect of lift. The longer the duration, the more the R.P.M. horsepower will be boosted, but it is at the expense of lower R.P.M. horsepower.
As we all know, it's a bunch of trade offs. What one tuner might think is a good trade off, another will think its a bad trade off. That is when the debates will start.