No Structure: "Tell me about yourself" is NOT an exciting first question. [Put together a structured interview that finds out exactly what you need to know about the candidate.]
Failing to Discover Capability: Interviewers who don't identify what they need done (performance objectives) can hardly find out if the candidate can do the job. [Clearly define objectives, then ask the candidate to tell you what they've done that relates to your objective.]
Behavioral Interviewing: Nice to know that someone can tell you about their leadership skills, being a "team player", etc., but unless you ask about these skills in the context of your objectives, you will simply get well-rehearsed answers. [Ask how the skill was used in a similar situation to your objective. Example: "How have you exhibited leadership by improving morale and motivation to achieve better productivity?"]
Failing to "Recruit": By staying in "evaluation" mode, some interviewers don't sell the candidate on wanting to work for the company. [Create balance by incorporating recruitment into the interview- like a first date – the meeting goes two ways.]
Repetition: Candidates often meet 5-10 people in the course of an interview day at the prospective company, and sometimes they all ask the same questions, and all give the same company description. The candidate leaves NUMB! [Assign different areas of questioning to different people, if possible, based on their expertise. Example: Have HR ask personality questions; have the Engineering people ask technical questions, etc.]
Trying to Find a Clone: Many interviewers try to find the same traits they already have, not realizing that a complementary set of traits may be of greater benefit. [Seek balance on your team by ensuring you look for people different than yourself.]
Relying on Your Intuition: Too many employers hire based on their "gut" feeling. [Use objective interviewing questions first, to discover the true fit, and only then let your intuition enter the scene.]
Lessons are repeated until learned. I hope some interviews improve as a result of these ideas.