How can I consistently perform prayers on time, what is the definition of "madhiy" and "maniy" for young people, and what is the ruling on performing ghusl for each of them?

Neglecting prayer is a grave sin that can amount to major disbelief (kufr akbar). To maintain it: perform it on time, pray in the mosque with the congregation, find righteous companions, stay away from sins and bad company, and use an alarm to wake up. Make your beginning filled with obedience and uprightness.