Just to note, you are required to carry your original documentation such as V5, Drivers Licence and insurance certificate... Photocopies aren't acceptable, although it's an idea to keep one of each document somewhere safe on the bike in case you lose the originals
Some people will say that you should mask your headlamp - I didn't bother and didn't have a single problem even with an HID conversion in a reflector that's 12-18" higher than the SV
As one who has had the pleasure of breaking down in lane three of a three lane highway at night in the snow in Europe I'd never leave without the hi-viz. Not only does it really make you stand out in the dark but it's an excellent way to get hold of the breakdown truck driver's attention
One thing nobody's mentioned yet, be aware that your credit card may be refused at some petrol stations / hotels etc etc - in our experience of Autoroute/bahn stations Total were a better bet than Shell but mine only worked a handful of times in the whole trip, despite informing Nationwide I was travelling. The same goes for cash machines... Get Euros asap, there's a machine in the Eurotunnel terminal building
Don't break the speed limit unless you have some money to burn, the fines are big and if you can't get the money they'll take the bike off you. If they have to take you into town to an ATM they're under no obligation to return you to where they stopped you (in Belgium at least) so you'll be walking
But by far the most important thing is to remember you're there to have fun, once you're over the initial "oh god things are different the drivers are going to kill me and I'm going to run out of fuel" relax and go with the flow. European drivers are much better than ours in terms of observation but they're far more aggressive - just be aggressive back and you'll fit right in
