Traditionally, many of the Central and Northern European countries' residents take almost a month's vacation in August(approx 20-25+ days @ yr) so be aware of that if you are used to camping w/o reservations.
Agreeing w/ crosscheck that the camp sites are different from ours; tight spots often covered with home brought AstroTurf and gnomes as opposed to flamingos. Many have restaurants on site and other attraction.
Not sure if this rule still applies but it can be cheaper to start and end a trip (rental) in Germany for a trip of 30 days or more since you won't be charged VAT/sales tax.
Fuel costs are much higher than you might be used to. Somehow you get used to it but utilising mass transportation is a good way to get around once you've reached your overnight destination. Plan to stay in the same spot for several days rather than wandering aimlessly and backtracking.
ETA: Look into getting a train pass for traveling in specific regions/ countries or through most of Europe.
Personally, I find it useful to research extensively before setting out: the music, any attractions that meet my interests, the culture but that's not for everyone; do what makes you feel comfortable.
Great local eats to make at the campsite or just eat out of hand can be found at the weekly markets. Any chain restaurants on the highways are in general just as predictable as the ones found here. You decide if that's a good thing or not in your life.
HTH
