Being good doesn't mean you have to agree with everything and everyone. You have to be fair and that sometimes mean you have to say NO and suffer the consequences.
If you learn to say no, you save yourself from a lot of trouble. It's hard at the beginning, you have to be prepared to face the music and loose some friends but those who you loose during this process aren't your friends. Friends don't abuse friends.
Helping others is the most wonderful thing in the world but there's always a limit. Help is reciprocal, not unilateral. You have to give in order to get and there's no such thing as always getting and not giving. There should be a balance, always.
That being said, you need to choose your friends and acquaintances carefully, show them you are a good person, always happy to help but not let yourself be exploited and abused.
The first key of being a good person is knowing your worth. Realise that you are great and special. Do good to people but take your brain while going good. Don't use your heart alone because if you do you are surely going to get hurt.
Give people what they deserve, don't let anyone take you for granted. If you see that a person doesn't appreciate your good then you should simply move on far away from such a one
Be with people that do appreciate your for your good works