Quote:
My main intrest area would be history, cancels, covers etc before 1920.
Most of the replies lean toward the collecting of stamps, but if I read your statement of preferences correctly, you are looking for information on postal history. That is a huge subject, but not well addressed in this forum, which as you can see is mostly stamp oriented. (Flak shield is up.)
The kinds of resources depend on the kind of postal history you are moving toward. For studies of fancy cancels the books by Skinner-Eno, Cole, ter Brakke, Weiss, and everything by the US Cancellation Club come to mind. For rates, the summaries by Beecher & Wawrukiewiscz give the basic info, but do not direct you in how to collect it.
If Postal History is becoming your thing, please continue to contribute here, but also visit the PhilaMercury website run by Richard Frajola.
http://www.philamercury.com Warning: they are not gentle or particularly inviting to newbie collectors there, but you will not get more direct answers to specifics PH questions anywhere else.
Meanwhile, if you could tell us what field of postal history (rates, routes, markings, regional/local history) you wish to explore, perhaps we can recommend some things.