United landed in Manchester on Tuesday after completing a near-perfect pre-season tour of the United States.
Despite only assuming his position just two days before leaving for the US, Van Gaal racked up victories over the Los Angeles Galaxy, Roma, Inter Milan, Real Madrid and Liverpool.
Almost everything went to plan, but the United boss is still not totally content with his squad.
The Dutchman has admitted he wants to sign new defenders before the season starts, but he concedes landing his targets will prove hard.
"Manchester United shall buy players when we can improve our selection," the United manager said.
"And that is a lot more difficult than you think."
Arsenal's Thomas Vermaelen and Borussia Dortmund centre-back Mats Hummels remain Van Gaal's top targets, although signing the latter is proving hard because the German club have already lost one star this summer in Robert Lewandowski, who joined bitter rivals Bayern Munich.
Another priority for Van Gaal is cutting loose the players he deems surplus to requirements.
Those who are surely in the most danger include Javier Hernandez, Nani, Shinji Kagawa, Marouane Fellaini and Anderson.
Van Gaal will not enjoy telling his unwanted players they have no future at the club, but he will not shirk away from making the changes he feels are necessary either.
"I won't come with the axe - it's not like that," Van Gaal said.
"We have to be honest
We have to give advice to the players now at this moment and not at the end of August
Then we can't change any more and they don't have a choice.
"Of course it's difficult to say something after two weeks but I think you have to say something."
United fans did not have to wait long to see Van Gaal's no-nonsense approach.
In his first press conference in LA two-and-a-half weeks ago, he criticised United for sanctioning a five-match tour that saw the squad clock up 13,500 air miles.
The United boss then criticised £27million signing Luke Shaw for turning up to pre-season out of shape.
And in training sessions he openly criticised his players if he thought they were not up to scratch.
Van Gaal had some stern words for Wayne Rooney on a couple of occasions, but the England striker has no qualms with the Dutchman's hard-line approach.
"He is a tough but fair manager," Rooney said.
The former Everton striker thinks the new coach has made a big impact at the club.
"He has been great," Rooney added.
"Since he has come in he has given us all a different way of looking at football, so it's been great for us and hopefully that will continue."
Van Gaal has implemented the same 3-4-2-1 formation he used with Holland in the latter stages of the World Cup.
That came as something of a surprise given that United only have three senior centre-halves b ut Rooney, who is used to playing in a 4-3-3 or 4-2-3-1 system, thinks the new formation is ideal
"It has suited the whole team," said the 28-year-old, who scored five goals in America.
"The manager came in and looked at the players we have and he felt it was best for our team
And obviously the results have proven it."
United's fifth and final win of pre-season came in the early hours of Tuesday morning when they beat Liverpool 3-1 in Miami to lift the International Champions Cup.
Winning the eight-team competition is not the highlight of Van Gaal's career, nor Rooney's, but the striker thinks United's 100 per cent record in pre-season bodes well for the season ahead.
"We wanted to win games and play well and we feel we have done that here," Rooney added.
"We've won a trophy and we did it by beating Liverpool, which is always nice.
"It's been a good few weeks
We are happy with the work we have done here so we feel we can go home and play well when the season starts."
United confirmed on Tuesday that a deal had been finalised with F K Vojvodina for the transfer of 17-year-old goalkeeper Vanja Milinkovic
The 6ft 7in stopper will spend the coming season on loan at the Serbian club before moving to Old Trafford next summer
Source : PA
Source: PA