systematization. I think, systematization is the biggest part of self-education. And a lot of people have problems with it. But why? Maybe because of school (i'm saying about russian schools). Teachers in my school didn't give me a motivation and I didn't interesting in it. Now I understand how important to find this motivation, because in real life nobody will teach you. You must do it by yourself. And an ability to systematize your mind is real helpful skill.