I love working with vocalists. And since I view each vocalist as an individual, I admit that it drives me more than a little crazy when I hear a pianist play a "generic" accompaniment without taking into account the personal style and identity of the vocalist they're working with.
I had a great opportunity to explore this yesterday. While playing piano for a Christmas party, I was asked to accompany a young lady who wanted to sing the standard "I'll Be Home For Christmas." No problem; I know the song and have played it many times over the years. I usually perform it in the traditional way, as a ballad with jazz overtones, like in this version by Michael Bublé.
When I got together with the vocalist for a brief rehearsal, though, I immediately noticed that she is much more of a gospel singer. While a jazz ballad accompaniment would have sounded fine with her voice, she mentioned that she had learned the song from Kelly Clarkson's version. I took a quick listen on my iphone via YouTube, and heard that even though Clarkson's rendition features some tasty jazz brass, the pianist is playing with a light gospel/r&b feel in 12/8 time. Have a listen for yourself:
I decided to adapt my playing by adding some triplets, simplifying the harmonies a bit, and playing some gospel-style accents and neighboring chords. And when it came time for my piano interlude, the singer's gospel phrasing led me to play more bluesy than I usually do on this song. I ended my solo with a series of strong blues tremolos and the singer came in with some impassioned embellishments on the melody.
The whole performance was exciting, but none of it would have happened this way if I had simply played the song the way I usually do. It would have been fine, but flat. And a missed opportunity!
So the next time you play piano for a singer, ask yourself what type of accompaniment really suits the vocalist best. You probably won't have to change much; just a slight alteration to the musical feel or tempo, and perhaps a few different chords or a new melodic approach. Be open to what the singer has to offer musically and let it influence what you play. You'll both be better off with this approach, and it will keep the music fresh for you.
Here are some free piano improv lessons for you, in various musical styles. Let me know if you have any questions!