Hi, I have recently been thrown head first into the fascinating world of philately. Going through some old inherited
boxes in the shed I have come across what I guess you could call a rather sizable cover collection of old saved business and personal correspondence of German origin. The correspondence is all in cursive old German (which I can't read), dating back to the early 1800's and contains material from old German states, German empire and material from both WW1 and WW2, allied occupation and beyond. Many of the covers are stampless as they predate the use of stamps in Germany. Of the stamped covers I have been researching the stamps online and found a great wealth of knowledge regarding many of them and as a result have been going down a fascinating historic rabbit hole. I had no idea this stuff could be so interesting!
Although there seems to be a wealth of easily accessible knowledge regarding stamps online, im finding it difficult to find information regarding covers, particularly of this origin. As all of this material is literally just sitting in stacks, in boxes, i'm trying to ascertain if there is any valuable articles in there to store differently with particular care.
So now on to my questions (sorry if these seem stupid, as im completely new to this):
In general what makes a cover valuable? Are there any blanket rules of thumb to this?
Is there value in stampless covers?
Is a cover more valuable if it still contains the contents?
How do I find out more detailed information regarding German covers?
I've read that the Michel catalogue is the best regarding german material, is this true?
Are there any English sources regarding German covers?
I have attached some random photos below as examples of some of the material - just by looking at it is there anything of particular note?
Thanks in advance!