Moe and OldBike, thanks for taking the time to respond.
I believe the rim is in fairly decent physical shape. There's no obvious (to me ) damage.
I've read about the pros and cons of truing a wheel with vs without the tire on. My theory in doing it with the tire on is that putting a tire on a trued rim and then inflating it will induce some stress that could "untrue" the rim.
When I decide to tighten or loosen a given spoke I usually make an 1/8 turn on that spoke and then do ~ 1//16 turn in the opposite direction to the spoke on either side of the one tightened. Not sure if that's good or bad.
Interesting point about pinging spokes before starting. I have noticed that just by feel, some spokes feel a bit tighter or looser than the rest.
All the wobble I was perceiving is side to side and was pretty easy to quantify using the dial indicator. I'm trying to figure out how I would use it to measure radial irregularity.
I've managed to get the wheel within about 7-8/1000". For a casual rider on a hybrid bike just trying to get some exercise I'm hoping this is good enough.
Again, thanks for the help.