I mean, in every movie, he always knows where to look for people. In addition, he also always goes to the town Laurie is in, even if she moved away. I think in H20, he actually sees she went to the school after going to her or Donald Pleasance's old house, but all other times he just knows where to go.
He's Evil! There's no reasons, he's just always at the right places, he loves toying with his victims, like that big elaborate reveal scene at the end of Halloween when Laurie walks into the room and Annie's corpse is lying on the bed with Judith Myers Tombstone there!!!! He loves to mess with his prey before he kills them!