Strategies for Solving Sudoku Puzzles

Sudokuwiki has excellent descriptions of solving techniques

Basic Strategies Chaining Strategies Exotic Strategies Uniqueness Strategies Getting Started Naked Pairs Naked Triples Naked Quads Hidden Pairs Hidden Triples Hidden Quads Pointing Pairs Box/Line Intersection Articles: Introducing Chains and Links Weak and Strong Links Strategies: X-Wing Family Sword-Fish Jelly-Fish Singles Chains Multi-Colouring Y-Wing XYZ-Wing WXYZ-Wing Y-Wing Chain XY-Chains 3D Medusa Remote Pairs X-Cycles (Part 1) X-Cycles (Part 2) Grouped X-Cycles Inference Chains AIC with Groups AIC with ALSs Forcing Chains sub group: Digit Forcing Chains Nishio Forcing Chains Cell Forcing Chains Unit Forcing Chains Almost Locked Sets Finned X-Wing Finned Swordfish Franken Sword Fish Pattern Overlay Aligned Pair Exclusion Empty_Rectangles Sue-de-Coq Death Blossom Bowman's Bingo Unique Rectangles Extended Rectangles Hidden Rectangles Avoidable Rectangles Sudoku X Strategies Sudoku X Pitfalls Jigsaw Strategies Killer Strategies Law of Leftovers The Killer Cage Convention Cell Combinations - An example cage combo Cage/Unit Overlap Innies and Outies Cage Splitting