A few sites that I always recommend to visit to learn more about silver:
1. Novica - great tips on how to clean silver. Especially great for those who has oxidized silver jewelry.
2. Overstock - has a section in their online shop that discusses all types of silver. Great to know what you have!
3. Auglen -This is a site with a guide on precious and semi-precious jewelry. Good to know why your silver jewelry tarnishes.
4. Simply Sterling - Explains what Quality Marks are, describes types of cleaning, as well as tells you that some people may have an allergic reaction to silver. Read it to make sure you are not one of them!
5. LiveStrong.com - talks about symptoms of allergies to silver that contains nickel.