The first six months as Real Sociedad coach could be "head-spinning" for David Moyes, says Steve McClaren.
Moyes was appointed manager of the Spanish La Liga side on Monday.
Ex-England boss McClaren said it took him time to adapt to coaching in both the Netherlands and Germany.
"My head was spinning and I felt nothing was going to work," he said. "After six months, you start to adapt and buy into their culture and get to know the league you're in."
McClaren, who was sacked from his position as England manager after failing to to qualify for the Euro 2008 Championships, moved abroad and was a huge success at Dutch side Twente Enschede.
He was named manager of the year in the Netherlands after guiding them to their first Eredivisie title in 2010, returning in January 2012 for another, less successful, year.
In between, he had a spell at German Bundesliga side Wolfsburg but was sacked in February 2011 after a poor run of results.
McClaren, who is top of the Championship with Derby County, said his experiences in both countries were "daunting" and "frightening", but added that they helped him become a better coach.