Wait until something is spotted, either Dinah or "helpers". Keep track of what is spotted in the left, middle and right position (I made an Excel Spreadsheet to keep track). Move cards one position and wait for something to be spotted, then again till each card has attracted something in each position. Don't change cards until you know it is too high or too low in each position.
This is the guide in Most Useful Topics for Alice:
https://www.fairylandgame.com/fbfairy/forums.php?tid=171905