Look around. See a friend? Do you see a friend in trouble or with a particular need? Then help them. That's what friends are for.
Is your friend a Christian? Encourage them. Lead your friend to Jesus. That's what friends are for.
Can't actually help your friend by yourself? Get some help and get the right kind. That's what friends are for.
The more you support your friend, the better friend you'll become.
John 15:13 (NIV)
13 Greater love has no one than this, that he lay down his life for his friends.