You can certainly measure spoke tension, but common sense is handy as well.

If you know "about" what a good wheel's spokes feel like (in terms of tension), then you can work to approximate that on your wheel. Squeeze two crossing spokes on both sides of the wheel. The drive side spokes should feel a little tighter/tauter than the non-drive side, but they'll probably feel somewhat close. If they already feel "really tight", then I might start by loosening the drive side nipples, perhaps 1/4 turn each, working around the wheel. I'd start at the valve hole and work around until you get back to the valve, to ensure you hit each nipple once and exactly once. This shouldn't change the lateral or radial runout of the wheel much at all, but should work to move the rim just slightly to the left. If, on the other hand, the spokes don't feel all that tight and you think they could be a little tighter, which actually describes most wheels, then start by tightening the non drive side nipples 1/4 turn, and work your way around the wheel, as described prior.

In either case, check the wheel center and check the spoke feel after one iteration of this. Is the rim centered...or at least better? If you feel it's good enough, then stop right there. If you feel it could use another iteration, decide then if you should repeat what you did before or if you should switch to the other side's spoke nipples to compensate.

Repeat those steps to slowly scootch the rim over towards the non drive side. Again, I'd let common sense prevail here and go with what feels good to you. If you think the spokes are about right at present, then maybe do one of each -- loosen the drive side a quarter turn, followed by tightening the non drive side by a quarter turn, and recheck. You need to move the wheel 1.5mm, which is not a trivial amount, so it may take an interation of two of working around the circumference to do it.

Just make complete laps around the wheel with your spoke wrench. A complete lap around ensures that you move the rim uniformly to one side. A partial lap means you move only part of the rim to one side -- and you'll end up with more lateral runout than you want (an "untrue" rim).

When this all works out successfully, congratulations -- you've just re-dished a wheel!