Get the "Book of Rifles" by W.H.B. Smith and Joseph E. Smith. This will help you with the WWII rifles. In addition, a "Blue Book Of Gun Values will also identify and put a value on those rifles.
A book Titled: "Pistols of The World, by IAN HOGG AND JOHN WEEKS, published by DBI Books inc is an excellant book for pistols.
Probably the most common rifle to start collecting is the Mauser 1998. It was produced, before and during the WWII era by many countries, in fact the U.S. Caliber 30 1903 Springfield Bolt Action, was a dirivitive of the Mauser Action. Mauser produced many rifles during this era and to have a complete collection of Mauser rifles is a collection of it's own.
[This message has been edited by Harley Nolden (edited April 17, 1999).]