Haas enjoyed a strong start last year, but the team lost its way and was forced to return to the car's Melbourne specification.
Kevin Magnussen and Romain Grosjean ran different specs for much of the second half of the season, a situation that wasn't easy to manage.
Steiner is adamant that the team has now taken a different approach.
"I'm taking things on board," he said. "We are not going to make mistakes like last season. I say definitely yes to that. We understood that, we are working a little bit different on it.
"There can still be mistakes. But I think if I would say we didn't learn our lesson and be stupid like last year, I mean, that wouldn't make me feel great, saying, 'No, I ignore everything that I learned last year, I just keep on going head down like we did last year.'
"No, we learned our lesson. We are humble, and we'll try to be like two years ago again. Let's speak about two years ago."
Steiner says the feedback from the drivers on the 2020 car in testing last month was encouraging.
"They made the right noises," he added."Obviously a driver is never happy, and especially if you think what happened to us last year - I mean, we were very happy with it, then it is ended up not to be good.
"So everybody's very cautious. We are very cautious in our prediction for this season, because we don't want to be, 'It's all good, it's all good,' then fall hard.
"So we do a diligent job and try to do the best and see where it takes us. But that's happened every year, just last year, the developments didn't work. So we ended up where we ended up.
"We are always very cautious in what we do. We are a little bit of a dark horse because we play it different. We change around a lot of things, normally here, there is a pattern in it, and we change the pattern a little bit.
"No, we are always cautious what we do and we just want to make sure that we've got we can use it, and come as best prepared as possible to Australia."