The Manchester City boss is well acquainted with the pressure that comes with having money to spend, having overseen an overhaul of his own playing staff at Eastlands.
Hughes' spending appears to be reaping impressive dividends as City have started the season brightly, but the Welshman has warned making the right decisions on who to sign is never easy.
City travel to St Andrews on Sunday with Hughes' advice ringing in McLeish's ears.
He said: "My advice to anyone in Alex's position, is to spend the money wisely.
"We have tried to do that, to increase the quality of the squad that we have and get the right players in here. We have tried to improve the standard and the depth of the squad.
Tough decisions"It depends on how much finance the new owners will make available for McLeish.
"When Sheikh Mansour took over here, everyone thought that there was an endless amount of money, which is not quite the case. We are working to a budget, maybe a little bit bigger than most, but we are working to a budget."
Hughes has some sympathy for McLeish, who is now in an unusual position for any manager more used to tighter financial controls.
He said: "It's not easy. There are a lot of things that will happen when takeovers go through.
"At times, you just want to be fully informed. If you are, and you are part of the process, then you're very much in tune with what's going on - and that is reassuring.
"That was the case when Sheikh Mansour took over. I was kept fully informed. I knew exactly what the long-term plan was, and as a consequence it was easier than it could have been.
"It is about communication, making sure that you are involved at every level and have an understanding of what the plan is.
"If you have that, then there's no reason why they cannot go quite smoothly."
Spend wiselyBut he added: "You must spend wisely. That's key to it. Irrespective of what budget you have, it is how you use that finance that is the key factor.
"If you spend well, which we feel here that we have done, then you can improve your squad and you can improve the level of performance that you produce on a consistent basis.
"With any money that comes into the club, or any perceived change in the levels of finance that you have, then there is a lot more interest.
"I would expect their profile will be raised if they do go into the market with some vigour."