Well it depends on where you are going and what you’re going to do.
MAPS, take maps like you don’t have satnav, ADAC maps are good, but check the scale of any maps being used, be careful of 1:1,000,000 million scale maps.
Special Maps, ADAC motorradtouren (ADAC-UEM) maps are great www it, also if your going to the alps there are a few nice alps motorbike sites with maps you can download and print off.
SATNAV, get a good one with up to date maps and lane assist for the motorways, and work out how to use it. The motorway network in Europe is complex especially around big cities and it constantly changes, use the motorways to get to other places. If you can use the autobahn do so, not to do 5000 mph but just so you can relax at your cruising speed.
If you do have pre-booked accommodation do a proper check of the location before adding it to your GPS, like verify the exact location using www maps and even print them off.
Compass (pre-satnav device), I have a floating compass inside the fairing of my bike, it comes in very useful.