Jesus didn't respond immediately to the blind men's pleas; He waited to see if they had faith. Not everyone who says he wants help really believes God can help him. When you think that God is too slow in answering your prayers, consider that He might be testing you as He did the blind men. Do you believe that God can help you? Do you really want His help?
Jesus told the people to keep quiet about His healing because He did not want to be known only as a miracle worker. He healed because He had compassion on people, but He also wanted to bring spiritual healing to a sin-sick word.