I'm thinking about planning a trip where I drive though every country in Europe. I know that there are people who have driven though every state in the US. There is information online about their plans, the trip, and the time it took. However I can't find much about this kind of thing in Europe.

I'm looking for strategies, other people's attempts, or successes. Driving is not necessary a requirement either, taking the train for some of it would be fine, possibly preferable.

So how would I go about it? Is there a prefered place to start? What constraints do the existence of connections (roads, trains, ferries) impose?