One rule of thumb is to experiment and see how your taste buds like the various schedules. Everyone has a different take on things.
I've developed my own standard hopping schedule(s) over the years.
If I'm going for an IPA or Pale Ale, or similar "hoppy" beer - I like to bitter with "clean" bittering hops, like Warrior or Magnum for minimum 60min boils. I love hop flavor, so I don't want to boil off the oils, so I keep my boiling times for my flavor hops to under 10 minutes.
My rule of thumb is that for every ounce of flavor hops that I boil, I at least match that amount after the boil (add them when the steam has died down). So, if I add 1 ounce for 5 minutes, 1 ounce for 2 minutes, then I'll add at least 2 ounces after the boil. The delicious oils will go away very quickly in the boil - you'll get some character from them, but really you get maximum flavor the less you boil them.
Adding them after the boil (around 170-180 degrees or so), will preserve the oils and they won't evaporate so readily, plus you'll retain a decent amount of aroma - and excellent flavor impact.