Learn to build the extended chords that give gospel music its sound and help support the harmonies of the vocals intrinsic to gospel hymns. These chords are primarily seventh and ninth chords. A major triad (three-note) is built with the first, third and fifth notes of the scale that shares the same name as the chord. In C, the notes would be C-E-G, which are the first, third and fifth notes of the C major scale. By playing a C major triad and adding either the seventh note of the C major scale (B) or the ninth note (D), you create the chords that are popular in gospel. Notice that D is the second note of the C major scale. It's also the ninth note because there are only eight notes in a major scale (counting the note you start on repeated as an octave). This means you continue counting from the beginning of the scale.
Practice the common one, four, five progression popular in gospel hymn music. This means the chords built on the first, third and fifth degrees of the key you're playing in. In the key of C, these chords are C major, F major and G major. To extend these chords, add the seventh or ninth note of the key you're playing in to the chords to fill them out. For instance, if your chord progression is C-C-F-F-G-G7-C, play the second C in the progression as a C7 (seventh chord), the second F as an F9 (ninth chord), the second G as a G7, and resolve back to the C. Moving from a major triad to a ninth or seventh chord fills the accompaniment out and creates movement in the piano part. This pattern works in any key.
Double chords to support the vocals. The spiritual message of gospel hymns is front and center of the hymn. Avoid overplaying and detracting from that message. Playing a chord with your right hand and doubling (playing) some, or all, the notes in the bass (left hand) helps support the gospel hymn harmonies and allows the lyrical message to flow through.
Play moving bass lines to create movement without overpowering the vocals. Play the notes of a chord as an arpeggio (separately as opposed to simultaneously) or the first two or three notes of the vocal line, and then move back to full chords. Focus on supporting the vocals rather than covering them up.