There are different styles, for instance Gospel music will use a lot of diminished seventh, Neapolitan sixth, and secondary dominant chords. In more classical hymns, it is typical to reinterpret them in either more chromatic ways, or for many, you will notice that they can be interpreted as having long stretches either in major or minor, because of the nature of the melody. You can experiment with pedal points, modulating up a step for more intense hymns in the last verses, etc. Find opportunities for chromatic bass lines. Have fun!
Walter Ramsey