Brett,
You're right, they are a little difficult to get to spin true.
I don't have any advice if you are using wood arrows, but if you are gluing them onto adapters for aluminum or carbon, this may help.
I use an arrow spin tester and I place a paper plate vertical against the tip of the tanto point.
I then make a very small "dot" with an ink pen where the point touches the paper plate.
Then I slowly spin the shaft and watch where the tip wobbles around the ink dot.
Sometimes there is an optical illusion if you spin them fast, the single bevel and tanto point look like they are wobbling but in reality they aren't, or at least not as bad as they look when spun fast.
I use hot melt glue and reheat and reseat the head on the adapter as needed until the tip of the tanto point stays on the ink dot when I spin it.
Hope this help a little.
John