Can't stress enough about educating yourself.

I found out many years ago, going to militaria shows, seeing an item and buying it only later to find out it was a reproduction. This was back before forums and also the internet existed.

The only thing I could do was purchase reference books and study them as much as possible.

With the internet and forums it has gotten easier but one still has to keep up studying books and the internet to stay ahead of what's being reproduced.

My library has more books than I do militaria collectibles. And even then, some of the books have items that are incorrect with what the writers list as original. It's a tough game to keep up with.