How should I prepare for my first GS-13 job interview?

Hello everyone.

I recently applied for a public health position at a GS-13 level within the U.S Department of Health & Human Services (HHS) via USAJOBS.

The application window was between: August 10th - 14th 2020 I used my non-competitive (NCE) status + education + experience to meet the qualifications.

Today I received am offer for an interview for this position. Although they stated that they were "very impressed" with my resume in the email, I'm very nervous for the interview. I never held a government job before but it's been a long career goal to crossover from non-profit.

I'm seeking advice on how to prepare for such interview. Also, has anyone used NCE to secure a position within HHS?

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