Perform Wudu
It is NOT compulsory to perform wudu before making du’a. However, performing wudu is a way of purifying yourself and getting into the correct mindset for speaking to Allah.
Abu Musa Al-Ash’ari (ra) narrated that the Prophet (saw), after the battle of Hunain, called for water, performed wudu, then raised his hands and said: ‘O Allah! Forgive Ubaid Abi Amir!’ [Bukhari]