England, fresh from home series wins against South Africa and the West Indies, head to Australia in November for a five-match series, desperate to exact revenge for the 5-0 drubbing they suffered in 2013-14.
Despite their successful summer, Root's men have had some wobbly moments, being soundly beaten in the second matches of both series by the touring teams.
Vaughan, who is happier with the state of the England team now than after their humiliating 340-run loss against South Africa, said it was crucial that the tourists avoid a hammering in the first Test at Brisbane, where they have a poor record.
"The way the team has played for the past few years is they have been inconsistent and he (Root) will want to bring consistency," Vaughan told AFP on the sidelines of the Betting On Sports conference in London.
"I don't mean lose a game, that happens, but the problem is when they have lost they have been hammered, bowled out in a session or a day.
"Against the West Indies in the second Test they fought their way back into the game after being outplayed in the first two days and only just lost.
"Lose the first day against Australia and you are gone," added the 42-year-old.
Vaughan, who said there would be two or three players on each side who would have question marks over them ahead of the first Test, believes several will be determined to put matters right after England were hammered under Alastair Cook on their last tour Down Under.
England regained the Ashes at home in 2015 so travel to Australia as holders.
"The last memory for these players or some of them of touring Australia is the 5-0 thrashing," said Vaughan, who captained England 51 times.
"There was turmoil, the (Kevin) Pietersen fallout, (Graeme) Swann retiring abruptly and management issues.
"They will try and put it right this winter. It won't be easy but if they can get something out of Brisbane then there is hope.
"Lose and it will be difficult, but above all don't get blown away so at least morale is all right coming to Adelaide."
Vaughan says it is crucial Root and the selectors are ruthless in the selection of the teams in the pre-Test warm-up matches.
"You have to win these so you arrive in Brisbane with strong morale," he said.
"Don't feel as if you have to play 13-a-side in these games, where everyone gets a piece of the action. Be ruthless in your selection, get your first 11 out and into form going into the first Test."
The former skipper said he is "excited" about the start Root has made in his role as England skipper but that it is too early to judge him.
"I've said before that Joe as captain has been given a great pass, with the players he has," said Vaughan.
"His declaration at Headingley (against the West Indies, setting them a huge target with just over a day's play remaining), that is the way I expect him to play cricket.
"Even though it didn't work, if they had caught their catches it would have done.
"I am excited how he has gone about his business and I am excited as to where he can take the team. However, I still don't think we will know fundamentally what sort of captain Joe is for a year or so."
The first Ashes Test takes place in Brisbane from November 23, with further matches to follow in Adelaide, Perth, Melbourne and Sydney.