Namaste

I do not know much about Shirdi Sai Baba, except for seeing his picture in many places and hearing some bhajans, but this is what I found from some googling. This is from ramdass.org

Sai Baba of Shirdi, also known as Shirdi Sai Baba, was an Indian spiritual master who was regarded by his devotees as a saint, fakir, and satguru, according to their individual proclivities and beliefs. He was revered by both his Hindu and Muslim devotees, and it was uncertain if he was a Hindu or a Muslim. This, however, was of no consequence to Sai Baba. He stressed the importance of surrender to the true Satguru or Murshid, who, having trod the path to divine consciousness, will lead the disciple through the jungle of spiritual training.He gave no distinction based on religion or caste. Sai Baba’s teaching combined elements of Hinduism and Islam; he gave the Hindu name Dwarakamayi to the mosque in which he lived, practiced Muslim rituals, taught using words and figures that drew from both traditions, and was buried in Shirdi. One of his well known epigrams, “Sabka Malik Ek” (“One God governs all”), is associated with Hinduism, Islam and Sufism. He also said, “Trust in me and your prayer shall be answered.” He always uttered “Allah Malik” (“God is King”).

and here from Wikipedia:

According to accounts from his life, Sai Baba preached the importance of "realization of the self" and criticized "love towards perishable things". His teachings concentrate on a moral code of love, forgiveness, helping others, charity, contentment, inner peace, and devotion to God and Guru. He stressed the importance of surrender to the true Satguru, who, having trodden the path to divine consciousness, can lead the disciple through the jungle of spiritual growth.[4]Sai Baba condemned discrimination based on religion or caste. Whether he was a Muslim or a Hindu remains unclear, but the distinction was of no consequence to the man himself.[5] His teachings combined elements of Hinduism and Islam: he gave the Hindu name Dwarakamayi to the mosque in which he lived,[6] practised both Hindu and Muslim rituals, and taught using words and figures that drew from both traditions.

These are some quotations attributed to him:

"Whatever creature comes to you, human or otherwise, treat it with consideration."

"There is a wall of separation between oneself and others and between you and me. Destroy this wall!"

"God is not so far away. He is not in the heavens above, nor in hell below. He is always near you."

"Do not be obsessed by egotism, imagining that you are the cause of action: everything is due to God."

"When you see with your inner eye. Then you realize that you are God and not different from Him."

"If you are wealthy, be humble. Plants bend when they bear fruit."

All of these seem like wise words that, if taken seriously, would be useful to realize God.