1. Using Porters 5 Forces The Se7en Deadly Sins

2. One Define the industry too broadly or too narrowly

3. Two Making lists rather than engaging in rigorous research

4. Three Paying equal attention to all of the forces rather than digging deeply in to the most important ones

5. Four Confusing effect (Price Sensitivity) with cause (buyer economics)

6. Five Using static analysis that ignores industry trends

7. Six Confusing cyclical or transient changes with true structural changes

8. Seven Using the framework to declare an industry attractive or unattractive rather than using it to guide strategic choices.

9. Further Reading The Five Competitive Forces That Shape Strategy - Porter (2008)