There is an absolutely PHENOMENAL book on tactics, oriented towards beginners, available for free on the web. It's called "Predator at the Chessboard", by WaltWard Farnsworth, and you can find it at http://www.chesstactics.org/
The depth of coverage is good for even intermediates. But he really takes time to explain the tactics in English, which makes it very understandable to beginners.