Once a person learns and understands how God loves him so much, and gave the ultimate sacrifice for him, he would surely want to do something for God in return. This is completely natural, but there is a proper way to do it.
Although praying, reading the Bible, going to church and helping others get saved are good ways to please God, the ultimate criteria is our faith. The Book of Hebrews says that without faith it is impossible to please God. What does that mean?
It means a few things. First, the doer should be someone who has already placed his faith in Jesus Christ as His Savior. Second, in whatever he does, he should keep the faith that God is watching, and he is doing all these acts of service for Him and Him alone.