With regards to the causes of the student of knowledge becoming firm in learning and retaining his knowledge of the Sharee’ah, the Noble Scholar Shaykh Muhammad ibn Saalih al ‘Uthaymeen rahimahullaah was asked:
Our esteemed father, what is the correct path that it is obligatory for the student of Sharee’ah knowledge to follow, such that he reaches that which he wishes for from pleasing Allaah, the Perfect and Most High and acquiring knowledge which is beneficial and which will be of use to him and the Muslims?
And what are the factors that will aid the student in memorising and making the issues firmly grounded in his mind and in not forgetting (them)?
Answer:
The most tremendous of the causes is that you have taqwaa (fear of and dutifulness towards) your Lord through obeying Him and leaving off disobeying Him – and your having sincerity towards Him and asking Him for (acceptance of) repentance and for help and for tawfeeq (success in attaining that which is good).
Then being meticulous in (attending) the lessons and in learning, and in preserving your time.
So these are indeed from the most tremendous of the causes.
And from the causes of that also is – studying with your colleagues and striving to (attain) the benefit such that the knowledge becomes established (with you).
So do not just content yourself with your reading and (attending) the lessons with the teacher – rather along with that, there should be studying with your colleagues who are of good character of (those issues) which are not clear to you such that the knowledge becomes established in your mind.
(Quoted in Wasaayaa wa tawjeehaat li tullaab il ilm p37 of Shaykh Muhammad ibn Saalih al ‘Uthaymeen rahimahullaah, translated by Nasser ibn Najam)
Nawawi's 40 Quizzes
Islam: The Study Guides 