Let us analyse few instances from the epic Mahabharata and try to understand how free will works.
Arjuna -> Jayadratha vadha: After Abhimanyu was slain in Chakravyuha by Kauravas, Arjuna vowed to kill Saindhava (Jayadratha) the next day (before sunset when the war ends) or kill himself if unable to do so. Krishna asked Arjuna as to why he made such a vow without consulting him or his brothers. Arjuna said that I have you by my side and victory will be with us.
Every event that happens post this proves how Krishna helped to make the vow (made out of free will) come true. Krishna asked Daruka (the charioteer of Lord Krishna) to prepare his chariot and keep it ready if needed so that he can fight. That night Krishna took Arjuna (in a dream) to the abode of Lord Shiva to get the blessings and the Astra (Pasupata).
This message (vow) reached Kauravas and the entire army planned to protect Jayadratha. The next day almost got over by the time Arjuna could reach Jayadratha and Krishna had to create the illusion of Sunset minutes before the actual sunset so that Arjuna could use that short time to kill Jayadratha.
Karna -> Shakti Astra: The Astra given by Indra, in return of Kavacha kundala, to Karna, was to be used only once to kill any one warrior (Arjuna). But Karna did not use it on the battlefield against Arjuna. This is intriguing as to why the most important weapon wasn't used to gain victory. Not that it was missed or wasn't part of the strategy, as we see this was always discussed in the night time and Karna wanted to use it the following day. On the battlefield, Krishna avoided a direct battle between Karna and Arjuna but the even more important thing is that the thought itself was stupefied.
Gandhari -> curse: After the Kurukshetra war Pandavas come to meet Dhritarashtra and Gandhari. Gandhari afflicted with grief wanted to curse Yudhisthira, but rishi Vyasa intervenes and stops her from giving the curse and advises her to show restraint.
After this Gandhari and others head to the battlefield where Krishna was cursed by Gandhari saying the Yadava dynasty would come to an end.
We see three scenarios of freewill here, one being aided for completion, one stopped at the thought level, and the third at the action following a thought. So what is the difference between them? Killing Saindhava might not be important but since Arjuna made the vow it had to be accomplished or it would hinder the bigger scheme of things. Similarly, Karna killing Arjuna would weaken the Pandavas and would lead to Dharma not being established. Finally, if Gandhari cursed Yudhisthira it would be a bad example for anyone trying to establish dharma and ending up cursed. Yadava dynasty coming to an end was part of the bigger plan so a curse related to that will make it easier.
So the bottom line would be if free will is completely going against the bigger scheme of things it would end up being hindered. Being on the side of Dharma and closer to God should aid it.