I am sure there are many more things to consider...and loads of sources for information about this sort of thing, but I thought it may be useful for me to contribute a few things I do, perhaps a few others could add their "real world" tips too?
Regardless of weather the countries require it, I always get an International Driving Permit. Only £20 from the AA. My reasoning is that I am a lot happier handing over that, than my actual driving license - and to date, no-one has questioned me handing over the IDP.
Everything paperwork wise is kept in a single folder, close to hand, which has individual plastic document wallets, arranged in a way that I know where everything is - makes border/police/etc checks quicker and I have found the more organised you are, the less the officials actually want to see it. Also means when I leave the car, it is all together, so it easily goes in the rucksack whenever I am leaving the car, I am quite paranoid about going anywhere without my documents.
Paper copies of all documentation incase the originals go AWOL in a seperate place.
I also have scanned copies of everything - stored securely online with encryption - my idea is if everything in the car did go missing, as long as we can get internet access amd a printer somewhere, we can at least get a copy of the documents back.
I take a very rough printed itineray of the route - i.e roughly what days we we planning to be in certain parts of the world - just to see if we are roughly on track. Very rarely looked at, only on the odd occasion when we are not sure on our progress.
Half a dozen recent passport size photos, just incase!
It is not often that you will find yourself driving a car, being offered a digestive biscuit and hesitatingly ask "Does it have any sand in it?". It was at this point that we realised we were in the depths of a great place