The best way to avoid having a bad job interview is to prepare ahead of time.
So practice, practice, PRACTICE your answers to the following questions:

Please tell me about yourself...
Why should we hire you?
What are your plans for the next year? Two years? Five years?
What do expect to get from this job?
What are your biggest weaknesses?
What are your biggest strengths?
Why did you leave your last job?
What would your former employer say about you if I called them today?
Why did you get into this line of work?
What make you want to apply to this company?
The interview is a two way street.
Remember you are also interviewing the employer to see if you want to work for that company.
You should have a list of questions in mind to ask the interviewer. Here are some suggestions.

What would you expect of me? What would my main responsibilities be?
How would my performance be evaluated?
Is there room for promotion?
Would there be any travel involved with this position?
Where do you see this company in two years?
How would you describe your management style?
How do you see me fitting into this company?
Most hiring decisions are made at the first interview.
How you come across in that interview could be as important as your experience and job skills.