"It's hard - you have learn, and work out how you deal with it yourself," she told NZ Newswire.
"It's just about controlling the nerves, because when you have so much adrenaline you push further and you run faster.
"That changes your run-up, so you've got to move that back, you've got to adjust your poles. There's a lot to think about."
McCartney's steep learning curve began in Portland, Oregon, at the world indoor athletics championships in March - her first international meeting at senior level.
"That was a huge competition, and I learned a lot from there," she said.
"I think I did get a lot of nervous energy that I maybe didn't control as well as I would have hoped.
"I'm hoping now, with that experience, going into the Olympics won't be so bad."
McCartney finished fifth at the world indoors, clearing 4.70m on her second attempt.
She has since stretched her legs at a couple of Diamond League meetings, finishing fifth in Monaco with 4.55m and third in London on 4.62m.
She says it's reassuring to have that extra experience on tap going into Rio.
"You just have to learn how to got through a situation without letting it worry you too much, and without getting overwhelmed."
