1. Dimensioning the part without understanding how it functions in the system.
2. Using co-ordinate dimensioning instead of GD&T.
3. Using RFS when MMC or LMC would work.
4. Arbitrary using the outside or convenient surfaces of the part as datum features.
5. Copying tolerance from similar production parts.
6. Labeling centerline as a datum.
7. Use of restrictive general or title block tolerances without using more generous tolerance where possible.
8. Requiring the drawing user to make assumptions.
9. Applying GD&T and datum last to the part.
10. Not controlling all features on a part (for size, location,orientation and form)