Thank you for your question!
The Brahmin code of conduct is not to have financial dealings among the spiritual family. It is better to go to a bank and pay their interest on a loan and resolve any financial issues that way than to ask someone privately.
I would suggest to follow the BK code of conduct when dealing with individuals who are not Brahmin souls. The reason is that you are opening yourself to deal with the popular: “You scratch my back, I will scratch your back.” Meaning that people may not ask you for money back, but they may “demand” for you to return the favor. That will put you in a bad spot.
There may be some exceptions to the above, but that is on a “case by case” scenario and according to your own “karma.”
In my experience, as we become more engaged into spirituality, material needs are reduced. You will not be “lured” by material gifts. You may accept them if they are something small in value as appreciation and to keep someone happy and then give it to someone else. The important point is that no one should fulfill a “need” in you.
If you “donate money,” please make sure that your donation gets to the cause that you want. Many times specially in this day and age, writing a check is an easy way to support an unknowing crime. It is your responsibility to follow up and make sure that those funds are being used properly; otherwise, there is a karmic return from that.