yeah i'm going to practice thanksIt's a good start. If you're like me you'll get better the more you practice. Best thing I found is to sit yourself down with some good reference pics (there's some really good one out there so you're in luck). Really have a good look at how the make-up is applied and the shapes it forms on the face and where things begin and end proportionally.
I guess it can be hard to achieve wrinkles on a fourteen year old face when you scrunch it up, but try scrunching and frowning and then applying the white and see if it has any effect.
Let us know how you get on, and as others have said have a lot of fun.