Delpy reprises her 2 Days in Paris role of Marion in the sequel, with the plot in the latest film centring on her character introducing her new boyfriend (Chris Rock) to her parents.
In an interview with USA Today, the French star admitted she felt tremendous pressure to keep 2 Days in New York running smoothly.
"You have to deal with the crazy actress, the insane director, the f**ked-up writer. I'm all three. I just have to deal with myself. It's a lot of stress," Delpy joked.
She went on to describe her strategy: "The stakes are high. I've learned that if you're really prepared, it's the best thing you can do.
"Everything is decided in advance, and of course, it falls apart when you get to the set, so you have to redo it. I plan ahead."
Delpy also revealed that she wrote a sequel to the critically-acclaimed 2 Days in Paris because she wanted to see Marion as a single parent.
"I wanted to explore more of Marion and her being with a new man, how life evolves for the better and worse. It's such a life-changing experience to have a child. I was interested in seeing how you manage that," she explained.
The actress added: "It's hard. You have to be organised. I can direct, act, write all day long, but raising a kid is the most complicated thing on the planet. I'm not the best mother. No one is."
Delpy previous revealed that she tries to emulate Robert Altman and Woody Allen while directing a film.
2 Days in New York is now playing in the US. The film opened in the UK earlier this year.
Watch Julie Delpy and Chris Rock discuss 2 Days in New York with Digital Spy below: