tell the court why you want to expunge your conviction. Consider including information like:
Your plans for the future;
The reasons you offended, and how your life is different today than it was when you offended;
How the conviction has hurt your employment chances;
If you have received any training or education since your conviction;
Any occurrence in your life that changed how you interact with your community; and
An y 12-step or religious affiliations you have.
reference:
http://www.saclaw.lib.ca.us/Uploads/files/Step-by-Step/ExpungingCriminalRecords.pdf
http://www.courts.ca.gov/documents/cr180.pdf
http://www.courts.ca.gov/documents/cr181.pdf
http://courts.ca.gov/documents/mc030.pdf