Voting for Oscar nominations runs Dec. 29-Jan. 8, and some folks may think it’s simply a matter of filling out a ballot. It is and it isn’t.

There are 17 branches in the Academy of Motion Picture Arts & Sciences, where voters submit nominations in their own category (directors nominate directors, and so on) and everybody nominates best picture. But it can be tricky. So here are some tips before voting.

1. Only one of your choices will be counted. The Oscar ballot asks you to enter up to 10 best picture favorites, and five in most other categories. The Academy and PricewaterhouseCoopers use preferential voting, a system designed to ensure that every voice is heard. But that means heard once. (The system is designed for elections where there is more than one “winner,” such as multiple Oscar nominees — as opposed to political balloting, designed to elect a sole winner.) So under preferential voting, PwC’s experts will count one of your choices in each eligible category  — and then set aside your ballot, which will not be looked at again.

2. List them in order of preference. Your No. 1 and No. 2 choices are important. In the first round, the PwC folks tally everybody’s first pick. At that point, some films may have enough votes to be nominated. If not, PwC takes ballots for the lowest-scoring films and “redistributes” those ballots, by looking at the second choice. This continues until films have enough votes to get nominated. Complicated? You betcha. If you want to know more about the system, click on the links in this story. But the point is that the order of your list is important: Don’t put your favorites in alphabetical order, or as they pop into your head.

3. Don’t assume your favorite already has enough support. There have been examples in the past few years of Oscar “frontrunners” who were not even nominated: Kathryn Bigelow (“Zero Dark Thirty”), Tom Hanks, Robert Redford. Maybe not enough people voted for them. But it’s entirely possible that many voters assumed they were shoo-ins and threw support to an underdog.

4. Conversely, don’t assume your fave is out of the running. Some pundits mistakenly think critics’ prizes are clear predictors of Oscar. Last year, “Dallas Buyers Club,” “Philomena” and “The Wolf of Wall Street” got very few top movie prizes in early handouts, yet all were Oscar-nominated for best picture. Bottom line: Vote for your favorite, not for whom you think might have a good chance.

5. Don’t fret about conspiracy theories. After nominations come out, everyone talks about Oscar snubs. But because of the preferential system, all 6,292 voters could name a film as best picture — but if each puts it at No. 4 or 5, the film won’t get a nomination. (A contender needs at least one first-place vote to get a nom.) So the Jan. 15 no-shows may not be snubbed… maybe they just weren’t the best loved.

6. Ignore voting myths. There can be five to 10 best picture contenders. For the past two years, the number has been nine, so some have claimed that’s the maximum. But, “mathematically, it’s absolutely possible” to have 10, says PwC partner Rick Rosas, one of the accountants who tabulates the ballots. Rosas also disputes the theory that it’s a good idea to enter only one title or person in the multiple slots. As stated before, you will only be counted once, but you should fill out other slots: If your top choice already has enough support, you could be giving the necessary vote for one of your other favorites.

7. Observe the deadline. Nomination ballots are due at 5 p.m. PT Thursday, Jan. 8. If you are in the middle of electronic voting at that moment, it won’t be counted; you need to submit by 5 p.m. If you’re voting by paper, PWC needs your ballot in the office by 5 p.m.; a postmark of Jan. 8 is not enough. (And, FYI, the deadline for choosing paper ballots has passed. Better luck next year…)

8. Pay your dues. Go to members.oscars.org to pay your dues and register to vote, if you haven’t done so. Otherwise, you can’t vote.

9. Electronic voting is safe. In the last few weeks, everybody in showbiz has gotten paranoid about the digital world. But “Security is always a priority,” says Brian Cullinan, chairman of PwC U.S. board of partners. “We’re confident we’ve taken all appropriate measures to ensure the security and validity of this year’s ballot process.” And if you need online help while voting, call the support center at 855-742-9140.

10. Follow these steps. This is all you need to know. You don’t really need to understand preferential voting, which is guaranteed to make your head spin. But if you want more info, there are links to two stories here.