The 17-year-old winger opened his account for the Reds on Saturday as they picked up their first home league win of the season against Reading.
"He just takes everything in his stride and is always willing to learn," Johnson told the club's official website.
"He has got fantastic attributes and I'm pretty sure and confident that this won't be his last goal in the Premier League that's for sure."
"He is a confident lad every day in training and a good lad as well. He is learning quickly."
Sterling joined Liverpool's youth ranks in 2010 before making his senior debut in March 2012.