I've seen a number of articles where filmmakers are giving their top ten tips for "micro-budget" filmmaking. And, for at least the articles I've read, there's a glaring omission.
If you want to produce a feature-length movie for next to nothing you have to start with a list of your resources - the things you KNOW you have for free. That includes equipment, props, costumes, food sources, vehicles, locations, virtually anything that can contribute to your production for NO DAMN MONEY.
Once you have that list you need to write and produce TO that list. Otherwise, you're speculating too much and your budget will bloat in a hurry.
You probably noticed I didn't include cast and crew as possible sources of free labor. Take advantage of that if you want/need to, but I would always advise paying people at least $50/day. Now, even $50 is a bit of an insult, but at this budget level you're usually hiring people who have other means of income or live with their parents or both. Still, pay them something.
Otherwise, get a list of your free shit and utilize it. Just make sure everyone gets thanked in the credits, a copy of the movie and an invite to the premiere.