Whats your best tips for smashing a job interview?

I have a internal job interview on Thursday and I'm super nervous. It's a 12 month temp job as a transport clerk and may get a permanent job after ad the company is expanding next year too.

I've always done very well in interview especially internal ones but I never get the job because they usually have decided who they were gonna give it too before they even put the job out but had to make it seem fair but they hired the mangers son but I'm trying to stay positive this time.

It's for a office job something I don't have much experience in but I need this jib bad so I can make a better life for myself and my husband. I just don't want to get nervous and sound like I don't know what I'm talking about

Whats your best tips for smashing a job interview?
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