You need to relax and be confident and you need to know your stuff. Are you going into the interview well researched? When they ask you questions are you answering them with confidence in your voice and in your face, and in your stance? Do you think about things that you can ask them-this shows interest? I am an employment specialist with Waukesha County in Wisconsin. I see so many people come in with the same problem. The problems that cut people from getting hired or being called back to a second or third interview are:
1. right off the bat not looking the part-dress for what you are tyring to achieve-over dressing is just as dangerous and under dressing.
2. wrongly aimed resume or application-sometimes you sound too good to be true, no one wants someone who believes she is perfect or better than others,or it can sound like you lack what it would take, and even confidence in yourself to do what it would take. Make sure you have a clear goal on paper and in your mind. Reach for the stars, but do realise that the stars are a long ways away and you need to go through the steps to reach them.
3. Know when to stop-you must know how to sell yourself, that is half the battle. The other half is knowing when the interviewers are satisfied with a response. Talk about highlights in your past employment or educational experiences-don't give a history, it is too long. Talk at a comfortable speed for you, make eye contact. When they are talking, nod your head at certain points of interest. Don't talk about what you want to do as if you would die if you somehow didn't make it happen-they like optimism.
4. Think outside of the box. They want people coming in with new ideas and a lot of energy. Don't tell them about Someone you admire and how they did things. Talk about who you admire, how they did things and how you would do it differently-but be careful not to put people down for accomplishment, say it in a way that makes it clear that you have done your research, you have respect for others in the field, and slightly express how you think you could help out.
5. Since you have been through the interviews twice already. Think about what was asked, how you responded, acted, and practice with those tools at home. Get comfortable with who you are, and with the words that come out of your mouth. Practice by yourself, with friends and with family. You can give yourself feedback, and friends and family see differently than you or each other, the feedback you get may make you more comfortable with the answers you already have, and can offer some advice on some answers you have given that may need to be tweeked. PRACTICE-it is to your advantage.
I don't specifically know how you "ruined" the interviews. but you have a head start now, you know somethings that might be coming. Use that. But most importantly be comfortable in your skin. Interviewers can smell discomfort, confusion, lack of self-esteem, and they will see that on your face. Go in like you already have the job, present your self with confidence, and beleive that you are on the first step to achieving your dream.