Buried in the endearingly manic jumble of thoughts and dedications in Olivia Colman’s dumbfounded Oscar acceptance speech last year – the one sealed as a classic by its panicked shoutout to Lady Gaga at the very end – was a telling thank-you that went largely overlooked. “And to Bryna,” Colman said, “who made me do things that I said ‘no’ to, but she was right.” It underlined the fact that Colman’s surprise victory over the frontrunner, Glenn Close, was not just a happy stroke of luck, but the result of a long and expertly calculated campaign.

The Bryna in question was Bryna Rifkin, the Hollywood publicist extraordinaire and dab hand at steering stars through the almost six-month marathon of “awards season”, from the essential autumn trio of buzz-building autumn festivals (Venice, Telluride, Toronto) to Oscars night. Rifkin’s client list is elite: in addition to Colman, she has in recent years carried the likes of Marion Cotillard, Ruth Negga, Willem Dafoe and Michael Shannon to against-the-odds Oscars recognition. All would have been put on a rigorous circuit of interviews, roundtables, talkshow spots and dressy appearances at umpteen precursor events and lesser award ceremonies – the very things a perennially working and not especially attention-seeking character actor such as Colman might have “said ‘no’ to”, only to be persuaded by a determined PR team that visibility is the key to victory.

Olivia Colman’s Oscar speech.

Merit isn’t the sole factor that launches a contender in the race, even when it may seem otherwise. This year’s six nominations for Bong Joon-ho’s Parasite, the first Korean film ever to receive Oscar recognition in any category, may have been applauded by detractors of the Academy of Motion Picture Arts and Sciences’ generally insular ways. But they didn’t happen in a vacuum. Neon, the film’s hip US distributor, has run a tireless campaign for the film that has succeeded by promoting the subtitled black comedy as a buzzy mainstream event, touting its 99% Rotten Tomatoes score on its marketing materials (in some cases, more prominently than the film’s big Cannes win) and – in something of a PR miracle – getting Bong (and his trusty interpreter, Sharon Choi) a guest spot on Jimmy Fallon’s late-night NBC talkshow in December. That’s an unheard-of coup for a foreign-language film-maker in the US: one can only imagine the frenzy of publicist negotiations it took to pull it off. A week later, when I asked him about the Fallon experience, Bong laughed and shrugged: “It’s not my world.”

Such promotion does not come cheap – $5m (£3.8m) is a typical cost for a single Oscar campaign, although for studios hungry and deep-pocketed enough, the sky is the limit. It is estimated that Netflix, still a relative newcomer to this game, spent upwards of $25m last year in its efforts to secure a best picture win for Alfonso Cuarón’s Roma – another critically adored, non-English-language arthouse film that didn’t look or feel much like a typical Oscar frontrunner, and thus needed a concerted push from its distributor to make voters view it as such.

Yalitza Aparicio in Roma … Netflix spent more than $25m promoting it. Photograph: Allstar/Netflix

The all-out campaign included all manner of Roma-related swag, from throw cushions to lush coffee table books, sent out to voters and journalists. And it worked – up to a point. It won three Oscars, but fell at the final hurdle to the cosily old-fashioned and very American Green Book – which not only spent a bit less money on the way, but weathered a variety of PR crises, including excavated #MeToo stories of the film’s director, Peter Farrelly, flashing his penis on the set of past productions, and an Islamophobic tweet from the screenwriter, Nick Vallelonga.

When Roma lost, some pundits speculated that voters had been put off by Netflix’s overeager campaigning, although given the obstacles the film was already up against – including industry wariness of the streaming model and the Academy’s general phobia of subtitles – it can’t have lost more than it gained.

The Golden Globes are another kind of race entirely. Eyebrows were raised last month when Taron Egerton won the Globe for best actor in a musical or comedy – not because his committed performance as Elton John in Rocketman was undeserving of the honour, but because of reports circulating on social media that all 90 voting members of the Hollywood Foreign Press Association (HFPA) had been invited to a reception for the film that also happened to be on his birthday. Nine years ago, an unlikely best-picture Globe nomination for the riotous Cher/Christina Aguilera campfest Burlesque probably had a little something to do with the fact that Sony had flown out HFPA members for a Cher concert and hotel stay in Las Vegas.

Taron Egerton as Elton John in Rocketman. Photograph: Paramount.

Egerton didn’t get an Oscar nomination. (Nor did Burlesque, for that matter, to this writer’s eternal disappointment.) Wooing Academy members is a subtler art; more about making them believe they love your film on their own terms. The disgraced Harvey Weinstein, once the master of opportunistic Oscar campaigning, knew this better than anyone. Spending an alleged $15m (at the time, a jaw-dropping industry record) on campaigning for the frothily charming period romcom Shakespeare in Love was the gamechanger that shaped the awards-season machine as we know it today: it beat Steven Spielberg’s solemnly macho frontrunner, Saving Private Ryan, to the prize on the strength of a cynically ingenious “love v war” campaign line that persuaded voters that the lighter contender was the one truly in their hearts. (The same year, a similarly button-pushing Miramax campaign for Life Is Beautiful netted it three wins, proving the Academy’s aversion to foreign-language fare can be overcome if the film is sweetened enough.)

Weinstein may be persona non grata, but his tactics endure. A recent campaign pivot for Joker, which leads the field with 11 Oscar nominations – but is also one of the most polarising contenders in recent memory – is worthy of the character himself: yes, the violent, nihilistic supervillain origin story is attempting a touchy-feely rebrand. Last week, as Oscar voting opened, a glossy sheaf of Warner Bros-sponsored content on the film’s behalf appeared in the industry trade bible, Variety, headed by a feature titled A Case for Empathy, talking up the film’s themes of class division and mental health awareness, and going so far as to conclude with a Gandhi quote: “The true measure of any society can be found in how it treats its most vulnerable members.”

It was the most brazen development yet in a campaign that has even turned the rebellious, publicity-shy nature of its star, Joaquin Phoenix (now the best-actor favourite), into a strategic advantage – with his unpredictable acceptance speeches (including his scorching attack on industry racism at the Baftas) and interview walkouts projecting the very image of anxious outsider-hood that Joker’s admirers respond to in its troubled hero. Is that just Phoenix being Phoenix or is it his own kind of anti-campaign strategy, the equally winning opposite of Colman’s funny, agreeable compliance? In this racket, it’s increasingly hard to tell. If he loses in an upset to Marriage Story’s star, Adam Driver, however, look no further than Driver’s publicist – one Bryna Rifkin – for an explanation.

The five biggest Oscars upsets – and why they happened

Grace Kelly wins.

Grace Kelly wins best actress (1955)

Judy Garland was the one to beat. Her all-stops-out, career-best performance in a Star Is Born movingly reflected her own career ups and downs, and the Oscars ceremony directors were so confident of her victory that they sent a camera crew to the hospital room where she had just given birth to her third child. Kelly emerged the winner for her against-type role as a dowdy, put-upon housewife in The Country Girl, proving the Academy’s eternal preference for unblemished ingenues over complicated legends – particularly when they are “brave” enough to strip away their glamour on screen.

Marisa Tomei wins best supporting actress (1993)

Marisa Tomei

It looked like a tight race between the four highbrow non-US stars nominated: Judy Davis was the critics’ choice, Joan Plowright the sentimental favourite, Miranda Richardson the ubiquitous breakout who was in everything that year and Vanessa Redgrave the beneficiary of best-picture heat for Howards End. Instead, in a classic vote-split scenario, they gave way to the one nominee who was not like the others: the Brooklyn-born newcomer Marisa Tomei for a brashly hilarious comic turn in the very mainstream My Cousin Vinny. Cruel rumours persisted for years that the award’s presenter, Jack Palance, had read the wrong name; in retrospect, voters simply chose the most entertaining performance.

Crash wins best picture (2006)

Crash.

Jack Nicholson’s ever-expressive eyebrows shot up a mile when he opened the best picture envelope to reveal the title of Paul Haggis’s tortuously contrived “everyone’s a little bit racist” parable. Ang Lee’s acclaimed cowboy love story, Brokeback Mountain, had swept all the other prizes that season, and seemed poised to make history as the first overtly LGBT film to win the top Oscar. But word of a homophobic backlash from the Academy’s more conservative members had been circulating in the industry: veteran stars Ernest Borgnine and Tony Curtis evidently spoke for many when they said they refused to see Lee’s film, and that faction tipped the balance.

Ex Machina wins best visual effects (2016)

Ex Machina.

Two types of films tend to win the best visual effects Oscar these days: lavishly expensive blockbuster spectacles or best-picture contenders looking to add another trophy to their haul. (Ideally, both.) Nominated against Star Wars: The Force Awakens, The Martian, The Revenant and Mad Max: Fury Road, Alex Garland’s low-budget, minimalist British sci-fi didn’t seem to have a prayer. But the work that went into creating Alicia Vikander’s sentient humanoid robot was so plainly ingenious and essential to her much-admired performance – it helped she was that year’s It-girl, winning that night for another film – that it pulled off a true David-v-Goliath shocker.

Moonlight wins best picture (2017)

Moonlight.

The circumstances of Moonlight’s win were themselves so stunning – as Warren Beatty and Faye Dunaway erroneously declared La La Land the victor, only to be corrected minutes later – it’s easy to forget just how breathtaking a moment it would have been anyway. Barry Jenkins’ melancholy study of gay black masculinity seemed destined all season long to finish second to Damien Chazelle’s vibrant LA musical, which landed a record 14 nominations and led 6-2 in wins as the final envelope was opened. But, in the wake of Donald Trump’s election victory, Academy members were perhaps in a more pensive, socially conscious mood, enabling a historic win.