The key to playing by ear is recognizing patterns. In gospel music (or any music genre), we have a name for these patterns, it's called a progression. You ever heard of terms like 2-5-1 and 7-3-6? Well, these are well-known and widely used patterns that are played in music. It takes the bass notes / LH notes of a song then tranlates them into numbers. These numbers represent scale degrees of the major scale of the key you are in. Here is an example:
7-3-6 in the key of C
C major scale degrees: C=1 D=2 E=3 F=4 G=5 A=6 B=7
7-3-6 = B, E, A
When finding a RH chord to go along with those bass notes, you start with the chords that are built off those scale degrees. If those chords don't fit, then do some experimenting and come up with chords that do fit. And, as it was said ealier, use your ear and see if you can figure out the chords that way. Here is an example of that:
chords built off 1, 4, & 5 = major
chords built off 2, 3, & 6 = minor
chord built off 7 = diminished
7-3-6 in C LH/RHB / B-D-F (7)
E / E-G-B (3)
A / A-C-E (6)
If you have no idea what I am talking about here, first thing you should do is visit the Basic Music Theory post at the top of this room. Then, once know some basis music theory, here are some links that may or may not clear some things up for you about progressions:
Basic Progressions:
http://forums.learngospelmusic.com/index.php/topic,15720.0.htmlMore Advanced Progressions:
http://forums.learngospelmusic.com/index.php/topic,15731.0.htmlExplaining Progressions:
http://forums.learngospelmusic.com/index.php/topic,18550.0.htmlProgressions Practice Routine:
http://forums.learngospelmusic.com/index.php/topic,18903.0.html