Some will have their eye on a striker to fire in the goals in the group stage, while others may be trying to net a big strapping centre-half to cement Cristiano Ronaldo.
However, Celtic manager Ronny Deila has a rather unusual item at the top of his wish list: A plastic pitch.
The Norwegian has been impressed with life at Paradise since he joined up from Stromsgodset in the summer, with the facilities at the club's Lennoxtown centre particularly impressing the 38-year-old.
Yet his heart is set on improving the set-up at the training base by constructing a dome to contain an artificial surface inside to get the Hoops through the roughest of Scottish winters.
Deila is no stranger to grim weather having spent his entire career playing in the Norwegian leagues before managing there.
And, after travelling long distances with Stromsgodset helped seal the club's first title for 43 years, the Celtic manager is keen to throw money at an indoor complex for his Bhoys, even if it means he misses out on a player this transfer window.
Asked if he would be comfortable sacrificing a new signing for a new pitch, he said: "Yeah. If you improve your players 10% it is much better than to buy a new player to try and solve the problem, but I hope for both!
"The most important thing is to get better artificial grass at Lennoxtown with a dome over it. That's one of the things I think is important to do because it's hard weather in Lennoxtown in the winter and the pitches are not so good. So to have the possibility of going inside and having quality training is maybe more important than a new player.
"Lennoxtown is fantastic. It's just the weather, if it wasn't for that then there would be no problem. But when it's windy and rainy so much, the pace goes out of the training and that's why it's important to go inside and do things.
"I'm never after my own CV. It's not why I went into football. I went into football to create things, and to do that you need to train and have quality in it. An indoor pitch is a positive step for the club and it will be good for the academy as well."
One of the products of that academy is Callum McGregor.
The 21-year-old netted the all-important away goal for Celtic in Maribor on Wednesday night, adding to his ever-growing reputation not just within Celtic Park but in Scotland.
Deila admits he was taken aback by the Scotland Under-21s talents, revealing the attitude of the midfielder is what makes him such a special talent.
McGregor is, of course, not the first young kid to emerge on the European stage in recent years, with Tony Watt famously netting against Barcelona in the Champions League two seasons ago.
Since then the forward's career has stalled quite severely - a Lierse loan move failed to win over the Hoops with him being sold to Standard Liege in the summer - but Deila has no fears the expectation or hype will have a similar impact on the latest academy graduate.
"It's two different people. It's more about individuals. It's about right or wrong," said the Celtic boss when asked about Watt's fall from grace. "McGregor is never going to take off in that way, he's training hard every day, he's a calm person. I have no worries for him. No worries.
"But you see the people who have problems, when they get it, and we're looking after them all the time. You see their body language and their awareness in all that they do. If a player is not performing he's not playing, and the players know that."
He added: "Callum has surprised me. He was one of many when I came to the club and in the first game I don't think I played him.
"Then he got a chance and he scored, I was looking at him then he played another game and was good and I thought he was a player. He has shown himself to be good enough when he gets the chance.
"I know that he is now performing well with Celtic so why couldn't he do it in there [Champions League group stage, if Celtic qualify]? If the others can do it he can do it as well."