Well there are different schools of thought on the gravity of the starter.
One says, it should be the same as your wort but not higher than 1.060. If you do this you simply aerate the starter, pitch the yeast, let it go into high kraeusen and pitch the whole thing.
The other says it should not be higher than 1.040 and you should aerate it as often as you can to keep the yeast in it's aerob cycle. This is where it grows the best and actually utilizies the maltose most efficiently. But in this case you don't want to pitch the whole thing. Settle out the yeast by fermenting it out or putting it in the fridge (the latter works best with ale yeast) and decant the liquid. Use the chilled wort to resuspend the yeast cake and pitch.
I'm doing the latter as it allows me to grow more yeast and don't have to worry about polluting my wort with a generic starter.
But If you are just starting out and want to have an advantage over simply pitching the tube/package, use the first method by making 1qt of starter with the same gravity as your wort.
As advanced reading:
there are goos "starter" articles in the tech tip section.