I think two main qualities of a saint are simplicity and humility. All the virtues and everything else follow.
If we constantly see the vastness of Nirankar around us, and His majestic powers thru His nature, we will remember how small we are. And Sangat should help us to stay focused on Nirankar. Basically, when there is no ego, there is no evil or sin ...... like anger, greed, pride, jealousy and hatred or desire to control others etc.
No ego also means love for all, helping others like your own, not hurting anyone intentionally.
ਨਿਕਟਿ ਬੁਝੈ ਸੋ ਬੁਰਾ ਕਿਉ ਕਰੈ ॥ निकटि बुझै सो बुरा किउ करै ॥
Nikat bujẖai so burā kyo karai.
How can anyone do evil, if he realizes that the Lord is near (& everywhere)? (Mehla 5, SGGS Page 1139)
Even a small child, knowing that he is doing something wrong, will stop doing it immediately when he sees a parent or an older sibling watching him.
We do not go over the speed limit if we see a police patrol car nearby or in the rear view mirror. Similarly we can not do anything wrong if we see Almighty God all around us.
A simple person does not need to lie or use unfair means to earn more. He has fewer desires and his needs are limited.
However, it does not mean that he should not enjoy the worldly pleasures. It means :
"Yallabhase Nijakarmopaattam, Vittam Tain Vinoday Chittam"
"Be content and happy with whatever you get through your own (sincere & honest) actions." (Adi Shankarachaarya)
Rishi Vyas Dev ji used to say "Saint neither demands nor rejects."
I don't consider myself an expert on this subject. I am simply sharing whatever I have learned from the Sadguru and some of the great saints that I had the privilege to be with and by reading Holy Scriptures.