The question is asked why didn't he just tell them to switch places instead of switching his hands? A beautiful message is derived from this by R' Chaim Volozhin. Normally when someone is standing in front of us their left faces our right and our right faces their left. Yaakov was teaching Yosef by doing this that when you relate to people i.e. someone who is standing in front of you, the normal way people relate is your left to his right and his right to your left. On a deeper level the right represents the strong side of a person whereas the left represents the weak side of a person. This alludes to a person's good and bad attributes the attributes on the right represent a person's good qualities and the left represents the bad qualities. When we normally look at someone else, we look at their bad qualities (their left) with our right, strong side, which magnifies the person's flaws. The opposite is true of the person's good qualities (their right) which we look at with our left, weak side, which minimizes their good qualities. Basically, when we look at a person we amplify their shortcomings and minimize their accomplishments, but when we relate to ourselves we minimize our shortcomings and magnify our accomplishments. Yaakov was teaching us that when we relate to other people as well we should relate to their right with our right and their left with our left.