Marty,
When finished, the drive-side spokes will have more tension than the non-drive-side spokes. The difference is very noticable.
Getting a wheel built properly requires several variables to come together at the same time: trueness, roundness, spoke tension, dishing.
I go for spoke tension first. I like my drive-side spokes very tight, they're creaking (I don't use a tension gauge). With taught spokes I go for true and then round. After getting the wheel round, I usually have to retrue it some.
With the spokes taught and the wheel true and round, it's time for dishing. A dishing tool is a necessity. Tighten the spokes OPPOSITE from the side with the gap. In other words, tighten the spokes on the left side to move the axle to the right. Go in 1/4 turn increments on every spoke. Theoretically you shouldn't affect true and round, since all the spokes will be tightened the same amount. Continue until the wheel is dished. If the spokes are getting too tight, you may have to loosen the spokes on the other side - again, in 1/4-turn increments.
Now start over. True, round, dish. The adjustments should be minor a this point, but it still make take 2 trips through the process.
Woody