In my opinion, every person has a true friend.I reckon a true friend shouldn't betray in difficult situations because it is unfair.If she/he is your good friend,you trust him/her.He/she knows your secrets.He/she shouldn’t let you down.
Another thing a good friend shouldn’t do is to envy your success because he/she should share your success and feel proud of you.
Also,a good friend shouldn’t ignore your interests because friends should respect each other and a good friend should care about your feelings.
And the last but not the least,a good friend shouldn’t support you if you are wrong because it is dishonest.A good friend should tell you honestly about your mistakes.
Actually,a good friend should appreciate your advice because you give it from your heart and have your best interests at heart.