1. Giving out references that don't sing your praisesYou don’t want a reference to damn you with faint praise. Ask if the person is willing to say you walked on water. If not, find another reference.
2. Laying out your résumé in a microscopic font
3. Failing to say glowing things about your former employer
5. Talking too much at the start of an interview
See all 10 ways plus the complete Forbes article