Answer:
Step one :
Pull up your grades and oncoming assignments ( if there are any)
Whatever subject you feel your lacking in dedicate to a separate piece of paper.
Step two :
Take these subjects and ask yourself questions. I would recommend if you can teach it, you know it . But Write what you feel uncertain about and questions from the lessons that you think you know it but don't know for sure.
Step three :
Once you have these filled out refine it. Now you have a basics of questions you are going to ask.
Step four :
If your nervous it okay, its always nerve wracking in the bening but in the end you'll both benifit from this.
Warning : A have my fair share of mean teachers but, coming prepare can show them that your serious about learning and they may change after doing this.
I hoped this helped!