I have had the privilege of working with two outstanding producers on feature films over the last 2 years. I worked as a producer with MaryLee Herrmann on Patrick Sheridan's Jimmy Said, and I am currently working with Mark Diestler who is producing Jack Gastelbondo's The Inner Room.
Making a feature is a monumental undertaking, and anyone who knows me has heard me advise against it in many cases, unless you really have a lot of set time under your belt. 90% of what you learn on set can be learned on a short. You can hone your craft in almost every respect without the added burden of the extra months of pre and post, and the added weeks of production. But that's just my opinion.
However, if you are going to make a feature, do yourself a favor. Get a producer. A good one. It is the best investment you can make (outside of a great script and cast...but if you don't have those you shouldn't be shooting in the first place))
There are lots of different kinds of producers, and I don't want to dissect all of that right now. What I do want to say is that you NEED someone to take care of stuff. What kind of stuff? I'm glad you asked.
Stuff like making sure the cast and crew is fed, that there is enough bottled water, that the schedule is worked out, that the locations are secured, that there is a first aid kit and a fire extinguisher, that there is money in the checking account, that there is adequate transportation when you change locations, that there is a cover set for inclement weather, that you have all the gear you need, that everyone shows up when and where they are supposed to, that there are extra scripts available, someone who can be both a peacemaker and a taskmaster, all of that and more ad nauseum.
And that's just some of the stuff you plan for. That doesn't count taking care of the many things that have to be dealt with on the fly. A producer's job can best be defined as the person who takes care of all the stuff that needs to be done to make sure that the director, cast and crew has what it needs to make the film. I'm sorry, but you just can't be an effective director/filmmaker when you are taking care of all of that.
I would work with either Mark or MaryLee again in a heartbeat because neither of them were reluctant producers. They didn't take the job because it was the only job left. They are producers because they understand the importance of what that position provides to the end product. Whether that means sewing patches on a shirt moments before the camera rolls, calling 4 electricians to get power to a remote cabin in the middle of a shooting day or spending months in pre-production trying to nail down all the details, they will do whatever it takes.
I also believe that a good producer should be someone that challenges you creatively, and with whom you craft a vision together. Bt if you can't find that, at least find someone who can take care of the details that you should not worry about once the cameras start to roll.