I did an unrelated bachelor degree and then worked in an unrelated field for a year before realizing I wanted to do film. I spent about three months sending out emails to various production companies asking them if I could intern and finally one decided to take a chance and straight up hired me, they wanted to train someone as a production coordinator from scratch.
To be honest, it was hell. I was the kind of place that takes advantage of young kids wanting to get into the creative industry, knowing there are 100 others willing to take their spot. So very low pay and many hours. But I learned heaps, made some shorts and eventually ended up at a lovely company, I now work in acquisition and development. Applying for MFAs for next year though as I want to focus on writing.
I'd say read lots of scripts and watch movies obviously, but also try to intern at as many places as possible - there is a ton of opportunity to learn there, plus potentially scoring some high value references for those applications. If you're able, try to make shorts and help out on other shorts.
Like Chris said, there are lots of people who come from unrelated fields. I would consider it neither an advantage or a disadvantage, the important thing is to have another way of demonstrating your interest in the field if you don't have a degree to back it up.
