Reasons That Will Aid One in Memorisation

1. Constantly mentioning Allāh سبحانه وتعالى (dhikr), and this happens through two important matters:
- Constantly renewing your intention. Ibn Abbās رضي الله عنه said, “Indeed, a man memorises as much as his intention.”
- Constantly reciting your daily wird and athkār. Allāh سبحانه وتعالى said, “And remember your Lord when you forget.” [18:24]

2. Staying away from sins. Imām Mālek رحمه الله was asked, “What is the most beneficial thing that will strengthen the memory?” He replied, "If anything would strengthen it, it would be the abandonment of sins."
Abdullāh ibn Mas’ūd رضي الله عنه said, “Indeed I believe a man forgets the knowledge he used to have because of a sin he did.”

3. Acting upon your knowledge. The Salaf used to say, “We used to rely on Allāh then on acting upon hadīth so that we memorise it.”

4. Being truthful and seeking Allāh’s help in observing His limits. “O you who believe! If you help (in the cause of) Allâh, He will help you, and make your foothold firm.” [47:7]

5. Writing, as the poet said, “Knowledge is a hunt, and writing is a rope, so tie your hunt down with a sure (tight) rope!”

6. Constant revision and perfecting what you already memorised.

7. Recalling what you memorised and explaining it/narrating it to other people.

8. Connecting that which you memorised with what you previously memorised.

9. Eating less and eating what helps in strengthening memorisation, like: raisins, frankincense, and drinking zamzam water. Getting hijāmah done also helps. It is said that there are some foods that inherit forgetfulness, like aubergine.

10. Time management, seriousness, and diligence. Some have said:
‎بقدر الكد تكتسب المعالي
Depending on the extent of exertion, you will attain the highest abode,
‎ومن طلب العلا سهر الليالي
And whoever seeks the highest abode will have sleepless nights,
‎تروم العلم ثم تنام ليلًا
You desire knowledge, but you sleep through the night?
‎يغوص البحر من طلب اللآلي
The one who searches for pearls dives the sea.

I summarised these points from the two books:
‎[متون أصول التفسير والتجويد والقراءات]
‎[عشر وصايا لقوة الحفظ وعلاج النسيان]