This is the technique, I use for Physics. I have previously used this technique with success in Biology, Chemistry and Maths. Whenever I sit to study, I take pen, paper, textbook/other sources, and start writing things which I need to learn/ memorize. This is not same as making notes for later, just put it in your brain as you write. Try to be as active as you can. If you are not self studying (i.e. studying at school/college) try to learn things as early as possible i.e. earlier than you are taught. The pleasing feeling you have when you know that you know things before hand is always motivating. I never bounded myself with syllabus of course of study. I was never strict to myself. Whenever I seat studying one topic, I usually end up studying something else without even realizing. The only problem I face applying this technique is EXAMS!!!!!. When exam is close, I attack past paper after past paper. If you feel like you can't answer anything, just look in your textbook, then only mark scheme.
I don't understand why people take endless notes for later study.