Immediately after last weekend's match the Irish squad cited indiscipline as the main reason for their defeat to the Pumas in Santa Fe.
Ulster prop Best said Ireland have learned what they should and should not do on Saturday at Jose Amalfitani.
"I think the biggest lesson is that we have to concentrate on more discipline, because we know we cannot afford giving away the same number of penalties, or we'll lose the game as we did on Saturday," he said.
"Discipline is something we should show as an Irish squad and Saturday was hopefully an exception."
Best captained Ireland for the first time ever in his career and will have another opportunity in the last game of the Argentina tour.
He admitted: "It's great to be starting another Test match.
"We are happy with how the pack went on Saturday, we had a pretty good game at set-pieces and the back row also played very well.
"This is another opportunity to show what we can do."
Best added: "Saturday's was a very physical game and next weekend's will be too. You have just a couple of days to recover."
"We have confidence in what we can do and how we can beat Argentina."
Ireland will use a very different line-up to the one in Santa Fe, with 11 personnel changes and one positional switch - Best being one of few players in both Tests.
The captain believes the use of so many different players will benefit Ireland.
He said: "The Pumas will work harder and will improve, so I think it's important that we do the same.
"We've made quite a few changes and that means the team will hopefully bring the same enthusiasm we did last week.
"If we do that again I think we can win it."