How do I know which direction I should rotate a node in an AVL Tree?
I think, I should get 37 as the root node 25 as it's left child and 52 as it's right child but I dunno.


You plan is correct. 

What you need to do is a left-right rotation as shown in the third column of the table below. That is,  a left rotation at node 25 followed by a right rotation at 52. It is symmetric to the right-left rotation as shown in the fourth column and as explained in Wikipedia.