Get the TourSaver 2/1 coupon book online before your trip. One glacier cruise (& you need to do at least one), will pay for the book. Stan Sephens tour out of Valdez is excellent.
As mentioned, check this forum's Alaska/Canada section for a LOT of information. Also at the very top of the forum is a 'Sticky' from last year's groupd that went and it includes an excellent checklist and things to do.
Drive slow. It's not an interstate-type of trip.
Reservations are not needed except for Denali National Park and July 4 weekend. Pull into a RV park early afternoon and you'll get a spot. Also, we boondocked about 90% of the time or stayed in public parks. It's so easy to do. Mike & Terri Church's Alaskan Camping book will give you many spots to do so and also lists RV parks. It's a must.
Stay IN Denali National Park for the best experience. We've stayed at Teklanika and Riley Creek. There's a lot to do from both locations.
The Milepost is excellent for historical information as you travel and for maps. Don't rely on it for campground information. All the ads are paid ads so they're all 'wonderful' campgrounds. Ha.
Plan to spend time in Canada and the Yukon, not just Alaska. They are all gorgeous areas. Yukon's government parks are great.
Cross the U.S. border and go to a Canadian bank for about $250 in Canadian currency. This will last you for the whole trip and back, especially if you use government parks. What you have left toward the end, buy some fuel with it.
It's an easy trip so don't be concerned about driving it alone. There will be thousands of other RVers on the roads. Traveling with someone else will really limit you as to what to see and do and how long to stay at each. Everyone travels differently. Have a great trip!