the first couple of steps are similar to starting any business- You should first start looking at the different types of company structures- S-corps, C-corps, LLC's, and Sole Proprietorships. The differences you should be concerned about have to do with how much legal liability you want to have, the tax structure, and the cost to create each company.
Once you've decided that, your choice will effect how you go about naming the company. So will the state/country you live in (just occured to me, I'm assuming you're in the U.S.). In some instances you may need to make sure that the company name you're using doesn't already exist in the region you want to set up shop (could be local to your state or you may want to make sure country-wide the name isn't taken).
(so far, no exciting film stuff!). You may want to talk to a lawyer or an accountant about how to do the steps above. I created my LLC 5 years ago. It can be done for a couple hundred dollars. You could pay more to have someone do all the paperwork crap. I did that by going to The Company Corporation that does it for you.
While all that's going on, you can think about what exactly you want to specialize in (or at least start doing since you may want to do 'everything'). Get biz cards made, a cell phone, domain, website (you probably know this stuff).
hope this helps! It seems daunting, but it's not that bad. Plus, when you've finally gone through it all, you'll be an ace and dishing out advice like me

heh, heh.
Mark.