Arrange your crew early!
This is a problem I had while shooting Revolution. The movie was for one of my classes, due about a week before graduation. I had it written, cast, and even had a decent location. And then I went to Vegas.
I was spending a week in Vegas courtesy of HBO and a documentary called Bailout 2011, and in doing so, I had neglected to obtain crew for any assistance with camera work or even holding the boom mic. Thankfully, I was able to con my father and my girlfriend into helping. I ended up directing, shooting, and editing the entire movie in one weekend. I guess my practice doing film racing paid off. At least I didn’t have to act too.
When you’re assembling your cast, make sure you get your crew too. Or be understaffed.