I can offer a tip that’s always served me well over the years, and has yielded many “I felt like you were singing just to me” type comments.
When on stage, pick three objects, that from your view, are just above the audience’s heads. One straight ahead, one left, one right. Usually it’ll be something like a clock on one wall, an exit sign above a door on another wall, and perhaps a sign or painting on another.
Then when playing, use them as your focus points, alternating between them. That way, you won’t be so nervous, because you’re playing to a clock, not focussing on anyone’s face, which can be awkward, and yet everyone in the audience will feel like you made a connection with them, and only them.
It works very well for calming nerves, and it avoids that awkward -
“I’m staring at that person! Oh no, now it’s obvious that I’m avoiding their gaze! Now I keep locking eyes! The more I try to avoid it, the more it happens! That girl thinks I’m coming on to her! That biker’s going to ambush me in the toilets because I keep pegging him out and locking eyes with him!” etc etc etc!!!