What are some practical examples of how Sikhs can cultivate honesty and integrity in their daily lives, both in their personal and professional relationships?

Respected Paramjit ji,
Waheguru ji ka Khalsa, Waheguru ji ki Fateh!

In response to your question, the undersigned wants to say that Guru Granth Sahib teaches a person/Sikh to become a righteous (ਸਚਿਆਰ) person and become one with Akalpurakh/Guru, who are embodiment of each other. The goal of becoming a righteous (ਸਚਿਆਰ) person was laid down by the First Guru Person Guru Nanak Sahib, in the first Pauri of Jap Baani itself, when he said:-

ਕਿਵ ਸਚਿਆਰਾ ਹੋਈਐ ਕਿਵ ਕੂੜੈ ਤੁਟੈ ਪਾਲਿ ॥ ਹੁਕਮਿ ਰਜਾਈ ਚਲਣਾ ਨਾਨਕ ਲਿਖਿਆ ਨਾਲਿ ॥੧॥

Once a person/Sikh achieves the goal of becoming a righteous (ਸਚਿਆਰ) person and becomes one with Akalpurakh/Guru, he will live a disciplined life and become virtuous (ਗੁਣਾਂ ਵਾਲਾ), get rid of vices and achieve emancipation/salvation in this life itself (ਜੀਵਨ ਮੁਕਤ) since there is no concept of salvation/ emancipation, after death in Sikhism.

Now coming to second part of your question as to how Sikhs can cultivate honesty and integrity in their personal and professional relationships. Both honesty and integrity in Gurmukhi mean ਇਮਾਨਦਾਰੀ, which is the biggest virtue of a righteous person.

You want practical examples of such persons, who had honesty and integrity. For this you have to take a cue from Sikh history, which is full of such persons. After Guru Persons, Char Sahibzadas, Panj Piaras, the undersigned is quoting just one example of a Sikh, who achieved the greatest heights of honesty and integrity in seven and half years of his Sikhi life, to which there is no parallel.

The person is Baba Banda Singh Bahadur, who became Sikh in October, 1708 in Nanded, in the hands of Tenth Guru Person, Guru Gobind Singh Sahib and along with his five years old son and 700 Sikhs (None of whom agreed to leave Sikhi despite all kind of material offers and threats) achieved martyrdom in June, 1716 in Delhi. He was a Sikh for seven and half years and the heights of honesty and integrity he achieved, perhaps, no Sikh will ever achieve. He laid the foundation of first Khalsa Raj, which was short-lived. After his martyrdom, the Sikhs never rested and had their homes on horses for almost ninety years till Ranjit Singh set up the Khalsa Raj and ruled for fifty years though the Sikhs were in a minority in his Raj.

Hope this helps. If you have any further questions, please do ask. If you find any deficiencies, please point out the same, for improvement in future.

Regards,
Your Brother

P.S. If you want to read about Baba Banda Singh Bahadur, please read a book by Dr. Ganda Singh by downloading it from Sikh Book Club. Also, please read about Lohgarh Fort where Baba Banda Singh Bahadur fought Mughals by clicking on the following link:-

http://www.lohgarh.com/the-largest-fort-of-the-world/