People only know what’s offensive to you if they’ve taken time to learn about you and preferably from you. The gesture that’s wrong. The label that’s even worse. The joke, the oversight, the sarcasm, or the innuendo.
If a person possesses good intentions and they still hurt you, it may be because they don’t know you. Spend some time revealing yourself.
Give them room to figure you out, to get to know you and not the image that they came with. If they neglect who you present yourself to be, perhaps they won’t be a good friend to you. If they stay, you can say that they already know who they’ll get. If they don’t use the information you gave them, you know what they think about you.