Jessica’s Answer:

I started as an assistant, became a development associate, and then started my own production company. Others in our office started as unpaid interns. Some people make the move from an agency to development. Then, I’ve met people who’ve come from completely different industries and their interesting skills combined with excellent interviewing has landed them a job in development.
This no single “best” way to get in. Therefore: 1.    Focus on building relationships with people in development

2.    Master interviewing skills

3.    Read books on script analysis, writing coverage, and studio executive biographies

If you have a question, put it in the comment section.
To your success!