Telling fakes is sometimes difficult as the fakers out there are getting better all the time. Fortunately, none of the stuff you are looking for is very valuable in and of itself, so there should not be too many fakes.
Good ways to judge authenticity:
1. If it's supposed to be old, it should look and feel that way. Unless we are talking about an treasured family heirloom or something that has been put away and forgotten for years and years, there should be wear marks, loose threads (cloth or embroidered insignia), dust, fading and etc. - or at least a little bit. An example is the Canadian Mother's Cross I found - the box it was issued in is worn, inside and out and the violet suspension ribbon has a good deal of wear on it.
2. Makers hallmarks or government acceptance stamps or marks. Most items have these somewhere, particularly metal insignia, weapons or other equipment. Cloth insignia don't usually have these marks, but you can usually tell by the way the item is made (see #3). Going back to the Mother's Cross, the name of the fallen soldier is engraved on the back and it's stamped on the back with the accpetance mark.
3. The item should look like it is supposed to and as if it were made for use in the period it was supposed to be made in. That is, if the item is a Canadian Mother's Cross, then it has a violet silk ribbon and is cast sterling silver, not a blue nylon ribbon and made of Stay Bright.
Two things to always remember:
1. Never spend more than you can afford.
2. Always deal with reputable people (no ebay stuff for me!).
There are some good dealers in US and some other countries stuff out there and I have dealt with the following. They are OK, if sometimes a little pricey (since I am US Army I have access to the exchange and clothing sales system for most stuff):
http://www.saundersinsignia.com
http://www.uscav.com
http://www.supertrooper.com
You can find more thru Google or Ask Jeeves, but Caveat Emptor :wink:
As far as books go, I have a good one from the UK that I bought years ago, but it is out of print. I typed in military collectables on Amazon and 10 different books on that came back, but I can't vouch for any of them.
What I would do is go to a big public library and do some research there first (cause it's free and you can actually look at the pictures, which you can't always do on the internet!). Another route is finding a local veterans or collectors society and visit one of the shows (sometimes you won't believe what you can find).
Hope that helps.
