Media playback is not supported on this device
Wednesday's match in Lyon will be Wales' first in the last four of a major tournament.
Coleman hopes Wales, appearing at a first competition since the 1958 World Cup, will become regular qualifiers.
"People think the end of this tournament is the end of this journey, but it's not," he said.
"It's part of the journey. The experience this group of boys will get from this, they'll be here long after I'm here. This success is part of the learning process.
"When I looked at the group we were in the tournament, I thought we were capable of getting out of the group.
"You never know who you'll get in the last 16, and then the quarter-final. I thought that was a possibility. I told the players that, that I genuinely believed we arrive at that stage.
"I didn't know what would happen after that, if I'm honest. But we've got a good team."
By guiding Wales to a brilliant 3-1 win over Belgium in last Friday's quarter-final, Coleman has already overseen his country's greatest footballing achievement.
They venture into the unknown on Wednesday with their first semi-final, whereas Portugal will be appearing in the last four of a major tournament for the seventh time.
Fernando Santos' side are the bookmakers' favourites in Lyon, though they have yet to win a game in 90 minutes in France.
They will inevitably look to captain and record goal-scorer Cristiano Ronaldo for inspiration, and his duel with Real Madrid team-mate Gareth Bale has been the subject of much attention in the build-up to the game.
Another Real player, centre-back Pepe, could have an important role to play as Portugal aim to subdue the threat of Bale, who is second in the Euro 2016 scoring charts with three goals.
Pepe returned to training on Tuesday having struggled with a thigh injury and, with the defender's confrontational style in mind, Coleman was asked about potential gamesmanship from Portugal.
"Our boys will know about the opposition. We do our homework on every team. We know their players individually and collectively, we know what to expect," he said.
"You call it gamesmanship, but sometimes it's being streetwise at this level. We've got better at that.
"We used to be far too honest. I'd look at what players used to do to us, and us in the same situations, and we'd be miles behind.
"Sometimes it's not pretty, or even ugly, and you can see it as negative. But anything you need to do to stay in the game, do it. It's streetwise, football smart. We've got a lot better at that in the last few years."
Chris Coleman believes there is more to come from his Wales side regardless of the result of their historic Euro 2016 semi-final against Portugal.