Watch the Finger & Thumb Free Stroke Exercise online guitar lesson by Andrew Leonard from Beginner Method for Classical Guitar
The exercise begins at 50 seconds. Two suggestions for practice: 1) think of each finger combination as its own very short exercise. Practice each right hand combination over and over until you can play it with ease. 2) Play the 5th and sixth strings using P. For example, you could play 10x with P on each string and then go on.
Again, we are using "My Favorite Right Hand Exercise". I find using this exercise with open strings very helpful because it allows me to direct all my attention to the proper right hand free stroke motions. Using only open strings allows us to avoid directing any attention to the left hand.