Good question, and these guys already put it really great, but I want to add what, I feel, is passion for filmmaking; it’s being honest with yourself about wanting to create the best project possible. If that’s what you honestly want, (and you don’t let anything like being paranoid people will find out your inexperience, or paranoid ego clouding your thoughts, or whatever) that’s passion for the project, and the rest of the departments will sense it, and will help you the best they can.
From a technical standpoint, acting is most important, script is second (I say that because you can have a really dull script that becomes interesting with some great performances, and bad acting is the first sign of a bad movie), production design, lighting, editing….
You have to be honest with yourself about everything. Look at the monitor and honestly ask yourself if what you’re looking at works. If not, everyone put their heads together and figure out why not.
Another thing is many of us “no budget” guys tend to compare ourselves to each other, and then we go to the local theater and rip the biggest blockbusters out there. There’s a shield we put over our eyes when we watch our own stuff that we remove when we watch the Hollywood stuff. Compare what you’re shooting to the latest Hollywood blockbuster and see how what you’re doing holds up. Are the performances there? Do you have a style? Is your idea of blocking simply two people standing face to face and talking for a whole scene?
Of course I understand the Hollywood blockbusters have a lot of money, but I’m talking about the simple things that don’t require a ton of money to make interesting; like blocking actors in a room. Would they really just stand there, face to face, in a kitchen, and do nothing but talk? Wouldn’t one of them grab a glass of milk, or do some dishes, or at the least, lean against the counter for a break from all that standing and talking?
Ask yourself what your honest interest is in making this movie. Would you be willing to take your name out of the credits if that somehow made the movie even slightly better? If the answer is yes, and that you honestly want to see a really great project come to life no matter what it takes, then you're light years ahead of most people.