Tommy was a try scorer in Saturday's 41-31 win over Argentina in the first game of Scotland's Autumn schedule but says the Scots can't afford to make the same mistakes when they take on the world champions.
Tommy said: "We scored 41 points out there, which is wonderful. But the reality is our opponents scored 31, so it was only a 10-point margin.
"It was great to get points on the board but we can't afford to make the mistakes we did against Argentina when the All Blacks come here.
"That is a key point. The feeling after the game has to be measured. There was a lot of positives in regards the rugby we produced.
"But we have got some huge games coming up - starting with New Zealand - and we can ill-afford to shift points in the way we did on Saturday, because the likes of the All Blacks will take them far more easily and on a far more consistent basis.
"We need to be really positive about the things we did well but by the same token make sure that some of the little flaws which crept in at the end are eradicated."