Apologies if this is obvious to you:
I've done a couple of wheels and the art is getting it true before any spokes are feeling tight. Snug, but not tight. Worth using something like coppaslip on the spoke threads, so it is the spoke tension you are felling, not any thread resistance. I used an axle in the soft jaws on my bench vice (vice rotated 90 degrees, bearings in the hub, so the wheel rotates at the side of the workbench). Then a plastic ruler flat on my workbench as a guide for lateral and vertical wobble. Works a treat. Don't get worried if there is a wobble at the point where the rim has been welded together, you'll never get that out. Just true the remaining 359 degrees of rim. This way, it's not difficult to get it to c.1mm true on both dimensions. That's more than good enough.
Once it's true, I then go round until all the spokes ring nicely, rather than 'thunk' when tapped with a screwdriver. Avoid a high pitched ('tink'). I do the tightening a small amount at a time, to avoid throwing the wheel out of true. Just 1/8th or less, increments and move on to the next spoke and so on, I keep checking it's still true. I don't tighten a spoke if it is already ringing, just move on to the next. I do not aim for the same note. That way, madness lies! Just get them near enough.
