One of the many things I did, to improve my hifz is this...
Before we do hifz or recite Quran, being humble - is to be aware of the many sins we did daily and ask Allah for guidance and forgiveness.
We also must be open to forgive ourselves for making such mistakes.
So before hifz, I normally do a Sunnat prayer of taubat /repentance or repeat Yunus a.s supplication 40x as dhikr..
لَّآ اِلٰهَ اِلَّآ اَنْتَ سُبْحٰنَكَ اِنِّيْ كُنْتُ مِنَ الظّٰلِمِيْنَ ۚ
Lailaha illa Anta subhanaka inni kuntu minadhdhalimin.
There is none worthy of worship except You. Glory to You.
"Tidak ada Tuhan selain Engkau. Maha Suci Engkau, sesungguhnya aku adalah termasuk orang-orang yang zalim
For more info: https://muslim.sg/articles/dua-of-prophet-yunus-a-s-in-english
Hope these helps.
Disclaimer:Do note that it's best to study hifz with a hafiz/hafidzah. It's not a journey to be taken alone (though it's possible). Though we may know the tajwid and basic of reading Quran, it's best to have someone who has been there done that and able to guide us, always.
Whatever I shared is what I faced in my life. May or may not be true or good for you. So always refer to asatizah/teachers in your country. What is best is from Allah what is not good is from me. Do help me spread what is good, with love. And do open your heart to forgive me for everything . Thank you.