Step 1: Call obstruction by the book.
Step 2: Call every penalty regardless of the circumstances of the game.
Refs calling penalties differently in first or the third, calling them differently in the regular season or playoffs, calling them differently based on who did what to who, making sure each team has equal powerplay time, ect..... THAT stuff needs to stop. Take the power away from the refs to decide out comes of games. If a ref sees a penalty, then they have to call it. Plain and simple. Fire them if they fail to do this ONE simple task.
If it results in too many powerplays being awarded, then players will adjust their game to compensate. Players will adjust to avoid taking penalties knowing they can no longer get away with certain things in certain situations. Scoring will increase when illegal-obstruction decreases.