Recommended fasts include Mondays/Thursdays, the three white days each month, six days of Shawwal, and Arafat/Ashura days — avoid fasting on Eid and Tashreeq days.
Voluntary fasting after Hajj is an excellent way to continue building on the spiritual foundation established during the pilgrimage. The most significant post-Hajj fasting opportunity is the six days of Shawwal — the Prophet (peace be upon him) said: 'Whoever fasts Ramadan then follows it with six days of Shawwal, it is as if they fasted the entire year' (Muslim). Since Hajj occurs in Dhul Hijjah (after Shawwal), this applies if you fast the following Shawwal.
Year-round recommended fasts include: Mondays and Thursdays (the Prophet's regular practice, as these are days when deeds are presented to Allah), the three white days of each lunar month (13th, 14th, and 15th — Ayyam al-Beed), the Day of Arafat (9th Dhul Hijjah, for non-pilgrims), and the Day of Ashura (10th Muharram, with the 9th or 11th). Important: fasting is prohibited on the two Eid days and the three days of Tashreeq (11th-13th Dhul Hijjah), so new pilgrims should not attempt to fast immediately after their Hajj rituals conclude.
Source: Sahih Muslim; Sunan al-Tirmidhi; Imam al-Nawawi, Riyad al-Salihin