Lisa gave good advice. Generally speaking, aussies are very active dogs. Which is the only reason that I don't have one. I love them, but I just don't have the energy to keep up with one, especially without a fenced yard for it to play in.
They are very bright and like to have something to do. If you have the time and are close enough to a place that offers agility, flyball, or herding, it would be perfect for him. I would spend as much time as you possibly can taking him for walks and playing with him. Games like fetch that require him to run would help him get out his energy. Because of their intelligence, you might want to try some doggy puzzle toys when he gets older. Aussies are like corgis... they need to keep their minds busy. A bored aussie will find something to do, and you likely won't like the results.