Do they move nearer to home to stay in the forefront of the mind of the manager of the national team? Or do they remain at a club that offers the chance of titles and glory?
Mark Walters, the former Rangers player, understands the pressures on Celtic's Gary Hooper. More than 20 years ago Walters was starring for a strong Rangers side but could not break into the national team. His chance came as he was about to leave Glasgow to join Liverpool.
"I was technically still a Rangers player when I won my cap. It was at the start of the summer when I moved to Liverpool,'' said Walters of his only appearance, against New Zealand in 1991. "Graham Taylor was the manager and had seen me play for Aston Villa before signing for Rangers, so that helped me. But playing in Scotland was a problem. I may have got a call-up a little bit earlier if it wasn't for that. We had great players at Rangers and I didn't think it was a backward step, but it didn't help my England chances."
Walters, too, was in direct competition with Chris Waddle and John Barnes, and concedes Hooper faces less daunting rivals for an England spot. The Celtic striker is the only Englishman to score more than one goal in the Champions League this season and Walters said: "Gary has been able to score in the hardest competition in the world. He just has to be consistent, keep scoring domestically, and if he can score in the Champions League it will boost his profile."
The 25-year-old has been courted by Norwich City and the striker may believe moving south would enhance his prospects. But Walters cautions against such a move.
"I've played against Norwich and Celtic and I know which club I'd rather play for. If he has any sense he'll stay at Celtic as they are the bigger club,'' said Walters, who played more than 100 times for Rangers from 1987 to 1991. "He'll win more titles at Celtic, but it depends how long he can put up with not achieving other ambitions. Norwich are in a better league, but Celtic are the better club. There is no doubt in my mind.''
But, in the age of big salaries and the Champions League, how important is an international cap? "I wanted to win leagues, score goals and play for my country. Not only does international football boost your career but wining a cap would be something to cherish for the rest of your life," Walters said, adding: "Celtic are a bigger club than Norwich – if that's his only alternative then I'd stay at Celtic. Norwich aren't guaranteed to be a Premier League club so you have to think of that. He could get a bigger club than Norwich if he stays at Celtic and scores more goals."
Walters also admitted there was a misguided snobbery in English football about Scotland when he played despite the presence in the Rangers side of those such as Terry Butcher, Chris Woods, Trevor Steven and Gary Stevens.
"People don't realise how big the Old Firm are. I watched Rangers play a third division game in front of 50,000 fans,'' he said of a visit north. "People couldn't believe that down south. If Aston Villa were relegated to the fourth tier of English football you would probably get 50 fans. It's difficult for people in England to comprehend how big the clubs are and how much pressure there is. That's maybe a problem for Hooper just now.''
Walters, speaking to promote ESPN's live coverage of Scottish football, dismissed any suggestion that Celtic's inevitable triumph in the Clydesdale Bank Premier League will in any way be devalued by the absence of Rangers.
"In 10 years, when people look at the records, people won't say that,'' said Walters. "If there was a better team in the league to push Celtic it would be tougher but all titles are valuable when you win them."
He did, though, make an appeal for some sort of compromise from Rangers and the Scottish football authorities over the future of the club. "The fans are the ones who have been harshly dealt with,'' he said, wishing Rangers a speedy return to the top tier.