Check out this wonderful site for a daily fix of learning. This is suitable even for brand new players since they provide explanations for any conventional bids. Thorough discussion of the decisions you are asked to make will help you improve your judgement quickly.
Every day they provide 2 bidding and 2 play/defense hands as well as a sample instructional flashcard. The level 1 hands are designed to improve the skills of less experienced players so that they can better understand the level 2 hands. The BridgeClues hands provide interesting and challenging situations, asking questions on what action to take, and then providing answers.