Filmmakers shouldn't make movies the way they've always been done if it means nothing gets done. The existing filmmaking paradigm was created by large companies with contract players, large pools of skilled labor and lots of money. You aren't a big film studio and don't have any of their resources, so why make movies the way they think they should be made?

No Unions

With apologies to current union members who are not allowed to work non-union jobs, you shouldn't work with film artist union members until they bring a significant advantage. Clearly at a point in your career you may want a particular director or actor but until the payoff is worth the investment (maybe never) you should seek other ways to get cast and crew members.

Cast As Crew

Forbidden by most unions but something you should consider is training cast to be able to fulfill certain crew positions. There is no reason an actor couldn't also be a production designer. One person could easily oversee the look of a set and then perform a scene on that set. Nothing precludes the director of photography from also running the camera or boom mic once the lighting has been properly set up. You can't overlook this kind of creative multi-tasking when you're in a low-budget situation.

Crew Member Cross-Training

Also disallowed by most unions, crews should be able to back up each other in case of absence or emergency. Crew members need to be forthcoming with knowledge on their particular specialty so the production can proceed if they were missing or a sudden surge in labor made it necessary for more hands to help with a certain aspect of production. If you have a small crew of five, the boom mic operator could hold a bounce board or run the camera when shooting an outdoor scene with not sync sound needing be recorded.

Self-Financing

You don't need other people's money. You don't need that much money anyhow. There are many ways to finance a small movie that doesn't involve grovelling for money or compromising the content of the film. If the crew is truly on board with the film they might be willing to donate, along with friends and family. As the producer and the one who should also benefit most from this venture, you should also put your money where your mouth is. You have people in your life that would be willing to help you make it happen, ask them.

I hope you see the point is not to disenfranchise union members but to empower small filmmakers. I believe unions fulfill an important role in mainstream filmmaking because a lot of money is made and it need be shared. But unions are built on a industrial model that doesn't fit with the milieu of no-budget independent filmmaking. So respect and support your union brothers and sisters, but don't work with them just yet.