Dalglish was quizzed on 17-year-old Sterling, who he handed a debut as a substitute when Wigan visited Anfield last weekend.
The boss said: "We need to have common sense and make sure we do a professional job on any of the kids coming in.
"Anybody who comes here must have a chance of being a professional footballer, but he's got a much better chance if we face reality. We've got to be realistic with him.
"At the same time we've got to be appreciative and realise it doesn't matter what age they are if they're good enough.
"But there is a bit of time to go yet on all of the kids. Last year we threw in Jack Robbo and Flanno and it never fazed them, but physically they were a bit stronger than Raheem.
"Every case is going to be different so we've got to look at them all individually and manage them, because we want them here for a long time."