What are the matters that guarantee entry into Paradise and salvation from Hellfire after repentance, and does memorizing the entire Holy Quran save one from Hellfire?

Praise be to Allah who has accepted your repentance. Sincere repentance is accepted from everyone who offers it with its conditions: abandoning sins, resolving not to return to them, and regretting having committed them. Memorizing the Quran and learning Islamic knowledge are among the most important ways to draw closer to Allah. The path to Paradise is by performing all the obligatory duties, abandoning all forbidden acts, then striving in supererogatory acts and abandoning reprehensible acts. Focus on mending your heart and guarding your tongue. What will help you in this is the companionship of righteous people, frequenting mosques, attending circles of remembrance (dhikr) and gatherings of knowledge, and reading easy-to-understand books and reliable fatwas. And the pinnacle of this is reliance on Allah, seeking His help, and asking Him for guidance and success.