Otago Boys' qualified for the final against St Kentigern College after beating both Christchurch Boys' and Napier Boys'.
Renton, a halfback and boarder at the school, from Wanaka, was one of the best for his side in those games, clearing the ball effectively and kicking at the right time.
"I've always had a ball in my hand and try to use width. It's developed a lot over the last few years," he said.
He has received tips from school coach Ryan Martin and practises drills to strengthen his wrists and hands.
He also worked with Otago coach Tony Brown in pre-season training to develop the right technique.
It will be a big game against St Kentigern College, at its home ground, with 5000 supporters screaming for their team.
"It was the same in the South Island final, against Christchurch Boys' at Christchurch. They got stuck into us.
"We just need to stick together, help our team-mates out, keep positive and block the crowd out. It will be the biggest game of our lives. We know what we have to do. I'm looking forward to it."
A win on Saturday would make the 2012 First XV the best in the school's 149-year history.
"It still hasn't sunk in that we are going to the Top Four final. We have talked a wee bit about it. It will be huge for us."
Renton is not concerned about the size of St Kentigern's players.
"They have got some big boys, but so have we. We have a big pack who work hard to give us backs good ball."
Renton was nervous before the South Island final against Christchurch Boys' High School.
"When I got the speech on TV over with, my nerves calmed down. I've been in some big games and know how to control myself."
Renton played a key role in Otago Boys' 30-16 win against Napier Boys' High School last weekend.
"It was a tough game. Napier was strong in the first half and attacked us at the breakdown."
A pep talk by coach Ryan Martin at halftime worked.
"We got better at the breakdown and got more ball. We got our pack going forward a bit more to give us clean ball."
Renton played a key role in inspiring the Otago Boys' comeback when he called the team together on the paddock.
"I told them that we've done this before and came back against Christchurch Boys' and can do it again."
His parents, Jenny and John Renton, have backed their son's sporting ambitions. Grandfather Graeme Renton is a former member of the ORFU management committee.
His mother is a keen sportswoman, who competed with distinction at the New Zealand Masters Games.
Renton intends to study commerce at the University of Otago next year and his rugby ambitions are to be selected for the Otago Rugby Academy and make the ITM Cup team. Long term, his goal is to make the All Blacks and become a professional rugby player.
Renton is also a member of the school's first cricket XI that will contest the Gillette Cup later this year. OBHS finished third-equal last year.
