4.
Freedom
This might seem difficult to do many times depending on who this person is in your life but sometimes the best way to love someone is to allow them to make their own choices, even if those choices end up being what you would consider a mistake.
It's hard to watch someone we care for make a choice that we know won't end well. We can do our best to guide them, show them other ways and give them options, but at the end of the day it's their life and they are the ones who are living it.
Allow this person the freedom to make their own choices and live their own life, even if it doesn't make sense to you. Let them know you still love and care for them even if they mess up or things don't work out as they planned.
And if they do come back to you in tears because of a bad choice they made, welcome them with loving arms. You may be tempted to say, "I told you so" but don't do that. It will just make them feel worse. Instead let them know you are there for them and that you will do what you are able to do to support them. Sometimes people just need to learn things for themselves.