Acing interviews

<p>I applied to two volunteer positions at school: international mentor and peer educator.
I got invited to a group interview and 1-on-1 interview. I have had only one interview for a part-time cashier position before (never had a group interview) so I was wondering what to expect and what they might ask. I really suck at interviews especially because my oral English is not proficient yet and also because of my shyness. I'm really desperate to get these positions.
Thanks!</p>