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Helm Mills, 27, and Clark, 36, trained together for just 10 months after being paired together for the last Olympics.
But Mills thinks the last four years' training could help them win gold.
"It [2012] was just a whirlwind, stuff going on we couldn't control and it all felt so rushed," said Mills.
"We had so much to do, whereas this campaign we've had a lot longer, broken down our sailing, broken down our teamwork and communication and rebuilt it again.
"It's taken time and it's a difficult thing to do but we're in a much stronger position as a team and in our sailing, so we feel really good."
Mills and Clark have proved a successful team, claiming a gold medal at the 2012 World Championships and silver in 2015.
They also won silver at the Aquece Rio International Sailing Regatta, a test event for next summer's Games in Brazil.
Having been runners-up at the last Olympics, Mills is hopeful the team can go one better in Rio.
"You can give your best performance and someone else on that day might have had a tiny bit more luck at the right moment, or their best performance might be better than yours," she told BBC Wales Sport.
"So it very much depends on whether we've given all we can and delivered our best. If we do that then I think we will be happy with where we come.
"But I feel if we can achieve that we will be on the top step of the podium."
Welsh sailor Hannah Mills says she and her crew Saskia Clark are in a stronger position for the 2016 Rio Olympics than they were for the 2012 London Games, where they won a silver medal.