How perplexing it must have been for passengers arriving at Baltimore's train station to see film-maker John Waters – ordained the "Pope of Trash" by William Burroughs – standing there, instantly recognisable with his pencil-thin moustache and pencil-thin frame wearing sunglasses and a sand-coloured silk suit darkened with splashes of rain, as though he had just been caught in a downpour.

Waters is synonymous with Baltimore; his hometown is where all of his films (including cult classic Pink Flamingos and mainstream hit Hairspray) have been shot. And it is a cloudless autumn morning. Having met before, he offered to pick me up at the station and drive to lunch. Upon closer inspection, it's clear the illusion of rain splattered on the cuffs of the trousers and the shoulders of the blazer are part of the design. As with most things with John Waters, everything that seems wrong is exquisitely right.

I slide into the front seat of his contemporary Buick, a very sensible car. It always surprises people who know him that he drives a Buick. "I like this car," he says, pointing out the Hampden neighbourhood we're entering is a mixture of hipsters and rednecks. "It's reliable. And I like that it's a totally unremarkable colour."

For someone who likes to be provocative, entertaining and outrageous with his work, his mode of transportation betrays his common sense. Waters's sensibility has always been playfully warped and he presides over a kingdom of misfits with a benevolent rule. But he is practical, too.

The Dogwood, where we're having lunch, used to be the local blue-collar cinema. He likes the idea of it now being a restaurant. And also, they hire staff that have been in prison.

"You never know if your waiter or waitress has been an ex-con and I think that adds a certain appeal." He laughs. "Ex-con rehab and fine dining? How often do you get those two together?"

He eats lunch every day in his kitchen; and he cooks for himself. Every meal is a recipe from Cooking Light magazine. "That is my bible."

On Sundays he'll plan out his meals for the entire week and shop for the ingredients. There is no waste. He'll plan out the exact amount in advance, and if he is having a dinner party – even if it's for 19 guests, which happened recently – he'll test the recipe out first. When he cooks, does he ever wing it? Never. "I hate recipes that won't tell you how many calories are in the meal. I need to know or I won't make them."

Are they always from Cooking Light? Always. Unless, he adds, it's a weekend. On weekends he'll splurge and eat "irresponsibly". Weaknesses are pasta or liquorice; he loves Lion's Wine Gums.

He weighs himself every two weeks on a Friday, when he's the skinniest, because he weighs the most on Sunday night. He stays within 5lb and while it's partly a health issue it's mainly because he likes to remain the same weight. Just in case. "Well, I'm a single man and every so once in a while a nudity clause is in my life!"

At 65, he looks ageless and his energy levels have hardly diminished. He's about to start a tour of 27 cities and his Christmas show will arrive in London in early December. It's about his obsession with the holiday – updated every year. It covers Christmas foods, what gifts you should give, how to deal with parents if they're crazy, religion, music, is Santa erotic, and so on. For the past 35 years he's been sending out bespoke Christmas cards and the list has more than 2,000 people on it.

Gifts are something he's opinionated about – for instance, gift certificates are the worst. Also re-gifting. "You can always tell. Ask for a receipt." Another bad idea is to give art as a present.

"I always say you should just reward people sexually. You'll never be able to print this…" he hesitates before continuing. I encourage him to keep going.

"If they give you a book that you asked them for, you fuck 'em. If they give you a book by a favourite author without you asking, you blow 'em. And, if they give you a book by a favourite author that you never knew existed, you rim them." He smiles. "To me, that is proper etiquette."

What if fans give him these gifts? "Uh no, I'm not planning to do that at the Southbank."

Traditions are important to Waters. For40 years he's had an annual Christmas party at his house. He used to have it on Christmas Eve but then everyone had a hangover on Christmas Day so it was moved. He spends the day itself with his family and this year he'll be going to his sister's in Washington and then the day after he'll fly to San Francisco, where he has a home. He also has homes in Manhattan and Provincetown, Massachusetts.

His routine is the same in every city. He works, has dinner parties. His homes look the same. Oriental rugs, contemporary art and books. And clothes in every home? "The key to my happiness – four sets of underpants in all four places. I can go to anywhere I live and not have to take clothes."

He loves London and it's the only place he goes on holiday. One week a month in September. The rest of the year he is always busy – writing (he's about to start his new book) and other projects. Certain things are part of his routine. He reads six newspapers – including the British papers – "Even the tabloids do it well" – and every day of his life, Waters writes his "to do" list out on a plain white index card. He pulls a creased one out of his pocket.

In the corner at the top is a number: 3196. How many days since he's had a cigarette. I'm next – the train I was on – then in no particular order: dinner at 7pm, Christmas shopping – figuring out an art trade – going over some things with his art gallery – talking to an old friend – finishing up something he's writing for the Wall Street Journal – going to the bank and getting 20 one-dollar bills because "you can only take ones" for his visit to a friend in prison; meeting his accountant. He takes a sip of black coffee. "That's my day."

When he's done with every file card, they go in a box. He's made an art show out of some of them. He also takes a Polaroid of everyone who enters his house. He's been doing this for 20 years and they, too, go in a file. "Think about it – if you take a photo of everyone who's ever been in your house – everyone you've slept with – everyone – I mean, I take pictures of the phone man."

No one has ever said no except one guy who thought it was weird. "So, I said, can I take a picture of your shoes instead, and he said, sure, OK." He laughs. "That's creepier I think!"

He looks serious when he says that sometimes it can be sobering. "You see people who've died and they don't know they're about to die – you see people get divorced, get fat, grow old."

Waters used to be in therapy. His therapist told him once, "Stop trying to make me like you." We discuss people who stay in therapy for 20 or 30 years and conclude it's possibly because they need someone to talk to.

"That's what shrinks are. When you've finally bored your friends with the same stories for the last time – you have to pay someone. It's like a hooker."

Lunch ends and before I get back on the train we stop by his house. My photo is taken. The house has a slightly gothic and Mediterranean feel. Every room is filled with floor to ceiling bookshelves. His collection of fake food is everywhere. Rubber sushi, spilled food, wax grits – the older items like a faded filet mignon look pitiful on a table next to a shiny bowl of ramen noodles.

He deposits me at the station and I wave as he drives away, an exceptional man in his invisible car.

A John Waters Christmas is at the Southbank on 5 December. Bookings on 0844 875 0073 or southbankcentre.co.uk