There is no need be scared. Just understand that there is a minority of people who have bad experiences. Be prepared for the positive or negative and understand that you will probably still be able to get GE if you are unfairly rejected - in that case you will just need to appeal the long way.

You might consider bringing a letter from your parents stating that they are supporting you as well as records demonstrating that you are indeed a student.

If you are not an obvious rejections (no criminal history, not a terrorist etc.) you will definitely receive conditional approval. The arbitrariness can come in during the interview.