well, what do you want?
A shooter?
A collector?
A 4 inch or a 8 inch?
WW1 or WW2?
If its just a luger, then buy a shooter and enjoy it and figure it out.
If looking for a collectible, then read here, and buy a bunch of books and learn from them first
Read the reviews on books first before buying the first ones, many inexpensive books are not the best ones to learn from.
Ed