Most folks will say to start by making sure your Airstream is water tight -- no leaks if you are storing it outside in the elements.
Then what we did was research, research, research and ask questions as we began to understand our tasks. Here's a great thread about work on another 1972 Ambassador http://www.airforums.com/forums/f332...-71467-12.html
Maybe it will be a good starting point for you.
We were most concerned at first about not making anything worse than it was -- making sure we knew what kinds of sealant and products to use -- and most importantly not to use.
We were helped so much by all the pictures that others had posted of their work in progress. Before we tore into a wall, we knew what to expect behind it based on photos on the Forum. I am using the "Royal" "We" here because maccamper did the work.
We have a 1974 29 ft. Ambassador with a rear bath. We were told our trailer was "camping ready" when we bought it. Well, we found out that was not the case. maccamper's first task was to completely re-do the rear bath area from the frame up because of water damage from the infamous rear bumper storage compartment with the piano hinge. Water intruded from the hinge into our bathroom floor and rotted it and did lots of rotting away of the frame. Our frame was pretty if you like lacy rust. You may come to be friends with POR 15 and have no fear about "dropping the belly pan."
We bought our Airstream in spring 2007. Here we are now getting ready to start our 2012 camping season and our "Emma" is better than she ever was. maccamper approached our renovation in phases so we've been able to camp as he did the work (you'll hear about camping in an aluminum tent).
One of the benefits of camping as you are doing your renovation is that you will gain so many rally friends who will be there to offer advice, share their knowledge and celebrate your accomplishments and feel your pain when something doesn't go as you hoped.
We were way out of our comfort zone on this project and learned so much. We have thoroughly our Airstream experience. You'll get discouraged and overwhelmed at times yet hang in there and hopefully you'll find the results well worth the effort (oh yes --- and the expense).
Nancy Mac (mrs. maccamper)
Wow . . . . someone already used the term aluminum tent and suggested the water tight before I finished this post!