Make the rules clear
Since games aren't full on reality simulators, the player can't know what can and can't be done in the game, unless the game makes it clear
Feedback
Always tell the player in no uncertain terms when they did something right, if you don't give the player proper feedback they might flipflop between methods despite already finding the good one but they moved on due to lack of clear feedback
Don't change the rules
The rules of solving the same type of puzzle should stay the same throughout the entire game
Allow all possible logical solutions
If an environment based puzzle can have multiple solutions to it, be sure to accept all possible solutions as valid
there were times when I got stuck in games because I found an alternate solution to a puzzle, but the designer had a specific one in mind
Don't make the player remember clues
This is more of a convenience rule, but I hate it when games force the player to remember things, what if I didn't play the game for a week between finding one of the clues and trying to solve a puzzle?