We have been to Alaska/Yukon 6 times now and I agree with all the advice given by 2Gypsies. It is a great trip and you will meet many other adventurers in your travels.
You will see the same people in various campgrounds as most will travel roughly the same distance as you every day - makes for friendly conversation in the evenings.
Travel on the upper half of your gas tank. Stock up on supplies in the major centers.
Relax and enjoy the journey - it is awesome. Should you have a problem along the road, don't fret. Someone will always stop and offer to help - it is the way of the North.