ANSWER:

You must advise her with good manners, knowledge, wisdom, and diplomacy. The best type of advice is the one that is given indirectly so you can post articles about hijab on social media so that she would see it. As the end of the day, she is a grownup person and accountable for her actions. We are not her baby sitters! 

I have a new revert friend . What she is doing these days is putting up photos on instagram revealing her cleavage and hair without hijab and using hashtags like #alhamdulillah. A friend tried to explain her but she is different when she talks to us muslims and different on her social media, and she still persists on it . What should we do now ?