How do you design puzzles so that people can figure them out? Often times when I design a puzzle, people who actually play it have trouble with parts that I thought would be simple. For example, say you have a Portal level where the exit is higher than the highest surface you can put a portal on. It seems obvious enough to me that a horizonal portal fling is not going to help, and you need to try something different. But I've seen some players futiley try it over and over anyway.

Your first few levels should be about training the player to think like you.

You find itbeasy in part because you know answer and often when people design a puzzle tame they make it with themselvescin mind which can resukt in things they find easy hard for othersvand thngs they find challenging trivual to other people.

Which is why for the puzzle game i've got to finish for the end of the month i've planned for the first 3 levels to be all about teaching the olayer to think the right way for the game.

Jonathan Blow has a very interesting talk about (mostly) puzzle design here:
http://the-witness.net/news/2011/11/designing-to-reveal-the-nature-of-the-universe/

Definitely worth a look.