Not that I am that good at following her advice, but: you have to look at your code in a more dynamic way; you try several designs, thus several abstractions, a

Not that I am that good at following her advice, but: you have to look at your code in a more dynamic way; you try several designs, thus several abstractions, and you know which abstractions are bad because they don't work for you at solving the problem at hand. That and some generic rules of thumb, like: prefer composition over inheritance.