I usually tighten the spokes evenly until the nipples are bottomed out on the rim butt not tight at all. Then I put it in my truing stand and mark it's position with the "feelers" (my stand is home made and the feelers are bolts). Then I flip the rim to see if it ends up in the same spot. If it's not I tighten spokes on whichever side it needs to go towards until it is centered on the axle and I can flip it and it ends up in the same spot. This is called "dishing" and I'm doing it wrong. (You're supposed to use a dishing tool.)
After that I spin the rim and look for high spots. I tighten spokes evenly until the rim is nice and round. Then I take out the side to side movements by tightening spokes to pull the rim straight. Once I get to fine tuning I will have to loosen some spokes. Then I check if everything is tight. It usually is by this point. Like Spike says. Not much flex once everything is tight. The spokes should make a ringing sound when tapped or plucked.
Everybody does this a little different. It's good to do a little research online if you've never done this before. Not hard. Just a few basic things to understand.
Good looking build....