Great advice here!

I think my solo playing benefits greatly from listening to and playing with others. The rocking blues bass gig is fabulous for "locking in" with the drummer, and so when playing solo I try to "lock in" with my mental drummer, even adding some bass lines along the way. The celtoid gig is helpful for playing without singing, working on alternate rhythms, mixing up the flatpicked/fingerpicked/hybrid styles and vocal accompaniment where I don't sing. The benefit is that when I play solo, some of the other "training" has been transferred. The duo with a fiddler helps me work on tempo extremes, syncopation, swing chords and the like.

My dear sister, who has a hearing impairment but is fabulously musical, was once very irritated by the constant (and to her very loud) drone of my high E string while playing open chords to a vocal melody. From that moment of enlightenment I've listened for that string to interfer with the melody instrument or voice. As a consequence, I often deliberately ease off the high E while chording. I won't do this with the 12 string as the 3rd course octave has its own way. This is also a good reason for owning a baritone guitar.

I might reiterate that the same strum rhythm pattern throughout a gig or throughout a song is too much. Songs deserve some dynamics, some variation, and some interpretation...even some silence (think rests) from the guitar.

Here's an example. The way I play Rights Of Man accompanying the fiddle (but it might just as well be a voice) starts with power chords (yup, 6 of them) in the first half, open chords in the second repeat, open chords with some walking/passing bass notes in the second half. We play it as a hornpipe, so it swings hard, even when I vary it by adding a half with a pedal note or drone like bagpipes. It almost seems like too much variety for one tune except that with repetition it seems to build, flow, and conclude. When I accompany myself singing, say, Move It On Over, I shuffle rhythm it with power chords, build to open chords and walking bass, then on to closed chords, not too much unlike what I do with Rights Of Man.

The singing part requires a kind of independence of voice which sounds like its own entity, yet "locks in" with the guitar beat, not being distracted by odd rhythmic things that can happen, like syncopation, triplets (by either), or dynamic "shots".

Practice, practice, practice. Listen to yourself as you play and played back on a recorder. Get a good vocal coach who's sensitive to accompaniment. Isolate difficult passages and work them over and over, but put it all together as a whole so you can get from beginning to end without glitches.

Good topic and interesting read.

Peace, Mooh