More Excerpts from "Solo Guitar Accompaniment" an article in Tune Up Magazine

Here are a few other important things to consider:

• Leave the melody notes out of your voicings where possible, especially as the top note. You will notice that this gives the soloist the maximum amount of freedom in phrasing the melody.
• Develop a sense of anticipation and the ability to interact spontaneously and decisively.
• This is not a skill that can be mastered overnight, but on that will come with a lot of careful trial and error.
• The task of making the best of a bad initial harmonic or the rhythmic choice is the gauntlet that must be run here.
• Work towards the development of a wide repertoire of harmonic devices that can be easily chosen and employed.
• Vary the textures you are using. Sometimes the most effective accompaniment is minimal. It is not necessary to use 5 and 6 note voicings having the root on the bottom.
• Consider all the options that are open to you, such as:
  • 2 or 3 note voicings
  • bass line figures (in the lowest octave of the instrument's range)
  • bass lines with chordal punctuation
  • contrapuntal melodic ideas
  • cluster voicings
  • constant structure
  • counter melodies with voicings
  • pedal point
  • harmonics/ special effects, etc. etc.
• (Most of these suggestions assume that you are comfortable playing fingerstyle, or with a combination of pick and fingers).
• Don't forget the use of space. It's not necessary to try to compete with the piano in terms of the weight of your accompaniment.
• Beginning with these concerns should provide a good start along the road to becoming a stronger accompanist.

An L.A. Times review of an appearance with vocalist Sunny Wilkinson may give you more insights into this topic.