What Al said. Urban speed limits in europe aren't always defined explicitly, in some places they use the city limits signs to mark start and end, so watch out for that.

The other thing I do, which can literally save your life, is stick something in my eyeline (on the screen maybe) that reminds me to ride on the right. On my first trip to europe I turned off a dual carriageway onto a minor single carriageway road and only noticed that I was on the wrong side of it for Belgium when a car came round the corner. Luckily far enough away and slowly that there was no drama, but...

Something to remind you is a good idea. Waiting for the high speed head-on impact isn't ideal for that

. Also useful for reminding you which way to look when pulling out of petrol stations etc.