1) Not easy to oppose the group you belong to
Bhishma failed to correct Duryodhana from his wicked ways, and he also failed to save Draupadi from being disrobed in public.
2) You may lose if you don’t understand purpose of your opponent
Yudhishthira succumbed to Shakuni’s challenge in the Pachisi (game of dice). He lost his kingdom, his brothers and Draupadi. While playing for second time, he lost all his kingdom in the game and was forced into exile for 13 years, which included one year in anonymity.
3) Use your words carefully
Draupadi joked “Andhasya Putra Andhaha” meaning “a blind man’s son is blind”. Duryodhana felt extremely insulted that Draupadi and her maids saw his embarrassing predicament.
4) Never ever believe your enemy
Lakshagraha house was built under the orders of Duryodhana and his evil uncle and mentor Shakuni in a plot to kill the Pandavas along with their mother Kunti. This incident is considered as a major turning point, since the Pandavas were considered dead by their cousins, the Kauravas which gave them ample opportunity to prepare themselves for an upcoming and unavoidable war.
5) In the battlefield, don’t be emotional
Before the battle, Arjuna, seeing the opposing army includes many relatives and loved ones, including his great grandfather Bhishma and his teacher Drona, has doubts about the battle and he fails to lift his Gāndeeva bow. Krishna wakes him up to his call of duty in the famous Bhagavad Gita section of the epic.