Here's how it works. The objective traits of a galaxy are "spinward, leeward, rimward, coreward", because the direction it's spinning toward, the direction it's spinning away from, and closer to/further from its core, are real things. So:
- Assume the core is the Earth. Put your feet toward it.
- Face spinward.
- Galactic north is on your left.
There's really no excuse for not having realized it sooner, I'd actually considered changing references to "orbital distance" in my aliens' dialogue to "altitude" (moving nearer or closer to the central body, namely a star), but I, being a Westerner, am only used to there being four cardinal directions.
Sometimes, Native Americans really do have insights Westerners lack, it ain't all hippie stereotype—in this case, because Navajo orienteering is based on "what is the sun doing" rather than "what does the map say".