What are the easy deeds with great rewards through which one can make up for past negligence in fulfilling their duties towards Allah?

The best way for a servant to draw closer to his Lord is by observing the obligatory duties and avoiding prohibitions. The obligatory duties are the Muslim's capital, and any supererogatory acts beyond them, such as reciting the Qur’an and performing good deeds, are a profit that brings the servant closer to Allah. One should maintain the remembrance of Allah Almighty in every state and at all times, especially the transmitted remembrances such as tasbih (glorification), tahlil (proclaiming divine oneness), takbir (magnification), and "La hawla wa la quwwata illa billah" (There is no might or power except with Allah). By avoiding prohibitions, fulfilling commands, observing obligatory duties, and frequently remembering Allah, a servant can catch up with those who preceded him and surpass those who come after him.