Review common interview questions. Practice answering them with someone else or in front of a mirror. Come prepared with stories that relate to the skills that the employer wants, while emphasizing your:

Strengths
Willingness to work and flexibility
Leadership skills
Ability and willingness to learn new things
Contributions to the organizations in which you have worked or volunteered
Creativity in solving problems and working with people

Figure out in advance how well you qualify for the job. For each requirement listed in the job posting, write down your qualifications. This can show you if you lack a particular skill. Plan how you will address this in the interview so you can convince the interviewer that you can learn the skill.