Some people have an inclination to help, often to their own detriment. This can come about because they, as some put it, “don’t know how to say no.”
Here are a couple of responses I heard recently that may be of assistance to help politely avoid making harmful commitments.
If someone wants you to do or agree with something that you have reservations about or perceive is not in your best interests, one handling is to respond with, “That doesn’t work for me.”
If someone pushes you to do something you do not agree with or understand, or want to think through the ramifications or need external advice on, something you can say that is not a straight up no is, “Let that sit with me for a while.”