Commodities are tough. As an asset class they move to a different beat than the market. If you want to learn about commodities pricing/trading you need to look at everything from how its produced, where its produced, its historical pricing patterns, and the general macro outlook.
I haven't the slightest clue when it comes to oil, silver or gold. All of my reading for fun has been focused on investing in equities.
For general "you can do it!" type books, Peter Lynch's "Beating the Street" and "One Up on Wall Street" books were enjoyable reads.
For some easy to follow investment strategies, Greenblatt's "You Can Be A Stock Market Genius" and "The Little Book that Beats the Market" are accessible and reasonably useful.
I've read a lot of value investing themed books. Of all the ideas out there, I think Value Investing has the best track record. Its more advanced and its dry as all hell, but Security Analysis is the bible of value investing. Anything by Buffet, Klarman, Marks, Graham and you're in good hands.