Hi James,
I fly here a fair bit of the time, what do you need to know? If you can be specific what you're looking for, maybe I can help, just PM me.
The first thing is which I note is that flying here is easier with just 3 Flight Information Services - Bremen, Langen and Muenchen Information (albeit with different frequencies). The good thing about these guys is that rarely do they refuse a traffic service - can I withstand the temptation to pose the question "what is the point of a basic service"?? Yes, I can......
The main issue you'll have is getting AIPs, they aren't published free of charge, the DFS charges for them - however if you know where you will be flying to, most airfields publish their aip on their website. Notable is that the AIPs actually show the circuit to be flown - so stick to these because at certain airfields - Bonn Hangelaar is the biggest stickler - if you don't fly in accordance with the published AIP *exactly*, they will summons you for noise infringements. If this happens to you, there's apparently a solution: claim you were taking avoiding action - avoiding a bird strike....
If you're flying to a lot of airfields, it might be worthwhile considering the "Landegutscheinheft" - it's 2 little booklets, one for north, one for south, which allows 3 landings at certain airfields and this can give some cost savings. Hannover and Paderborn / Lippstadt are listed, so it's not just the smaller airfield involved.
Notams, filing flightplans (when flying VFR only necessary when crossing international borders - with the exception of Austria where you don't have to file plans) can be found
here - access is free after registration....
As said, anything else, let me know....