Philosophy Pages
Philosophy Pages: Categorical Propositions
Introduces the method of categorical logic, as used in the deductive reasoning formalized by Aristotle. Author defines important terms very clearly and includes several good examples. A good place to start reading about logic.
Other
R. B. Jones: First Order Predicate Logic
Great introduction to basic ideas in predicate logic. Conveys fundamental ideas without using technical notation. A good place to start.
Stanford University
Stanford Encyclopedia of Philosophy: Logical Form
A terrific introduction from the Stanford Encyclopedia of Philosophy to the conventions of notation and form in logic, and indeed to logical philosophy in general. Discusses the logical semantics of propositions, description, analysis,...