Do not withhold it.

"Do not withhold good from those to whom it is due, when it is in the power of your hand to do so. Do not say to your neighbor, 'Go, and come back, and tomorrow I will give it,' when you have it with you."
  --Proverbs 3:27-28

God has given each of us the power to reach out to people and help them in whatever way the Lord directs us to do. When a brother or sister in Christ is in need of anything, whether that be food, clothing, or simply just godly fellowship and/or council, if you have it, do not withhold it from them.
If we shut the door on a neighbor, we are shutting the door on Jesus Christ Himself. He gives the power to reach out to others and help them, and so by not helping them, we are not only shutting the door on Christ, we are shunning His gift! Do not be the one to shun the gift. But be the one to accept and share.
You could do a world of good, if you only accept.