1. No names / labels / identifying information
2. Hanging with nails (even small ones!)
3. Not sewing far enough either side of the lines when paper piecing (although apparently the stitch length was fine...)
4. The usual cut off and unmatched points
5. Too much bulkiness in my binding join / binding not mitered properly at corners
Those are the only ones I can remember right now... I'm sure that I'm guilty of more!