The first thing is to renounce the kingdom and appoint Parikshit, the son of Abhimanyu as the king and Kripa as preceptor which they did.
Yudhishthira made over the kingdom to the son of his uncle by his Vaisya wife. Installing Parikshit also on their throne, as king, the eldest brother of the Pandavas, filled with sorrow, addressed Subhadra, saying, ‘This son of thy son will be the king of the Kurus. The survivor of the Yadus, Vajra, has been made a king. Parikshit will rule in Hastinapura, while the Yadava prince, Vajra, will rule in Shakraprastha. He should be protected by thee. Never set thy heart on unrighteousness.’
Arjuna had to give his Gandiva away as told by Agni Deva, the deity of fire
‘Ye heroic sons of Pandu, know me for the deity of fire. O mighty-armed Yudhishthira, O Bhimasena that art a scorcher of foes, O Arjuna, and ye twins of great courage, listen to what I say! Ye foremost ones of Kuru’s race, I am the god of fire. The forest of Khandava was burnt by me, through the puissance of Arjuna and of Narayana himself. Let your brother Phalguna proceed to the woods after casting off Gandiva, that high weapon. He has no longer any need of it. That precious discus, which was with the high-souled Krishna, has disappeared (from the world). When the time again comes, it will come back into his hands. This foremost of bows, Gandiva, was procured by me from Varuna for the use of Partha. Let it be made over to Varuna himself.’
"At this, all the brothers urged Dhananjaya to do what the deity said. He then threw into the waters (of the sea) both the bow and the couple of inexhaustible quivers.