How can advice be offered to sisters who deal with people to achieve personal gains instead of working for the sake of Allah?

A Muslim's interactions with others should be based on Islamic law, seeking Allah's pleasure. Allah has commanded beneficence, and the Prophet, peace and blessings be upon him, encouraged fulfilling the needs of Muslims, relieving their distress, and concealing their faults. Whoever loves for Allah, hates for Allah, gives for Allah, and withholds for Allah has perfected faith. Love for Allah is for the believer due to their religion and obedience, and hatred for the disobedient is due to their disobedience, and for disbelievers due to their disbelief. A Muslim is required to treat their Muslim brethren with kindness, help them, and desire good for them, regardless of kinship or worldly interests. It is permissible to exchange benefits and reward those who do good, but interactions should not be limited to these interests.