Scrabblette and I played Torres the other evening. The rules don't mention anything like "you're not supposed to add a knight to a castle your opponent has been building and get more points from it than her", but Scrabblette somehow inferred that rule. Let's just say my convincing win may not have been worth the sacrifice. Nevertheless, I think it was my first win at Torres.
Anyway, at the start of the game I had an epiphany. It's kinda obvious. Anyway - it takes one action point to move a knight to an adjacent square OR put him in one door and out any other on the same or lower level of the same castle. It also takes one action point to place a tower piece. So, rather than take multiple steps, place tower pieces to optimise the distance you can move a knight in one step.
There are other considerations of course, like "will placing this tower piece make it easier for my opponent to come uninvited into my castle?" But in general combing castle building and movement is an optimisation which might let me win at Torres occasionally.