How points are earned
What to do with them
Pick the end constellation first
Devotion is a graph, not a list: reaching a big constellation means paying for the small ones on the way. Decide the destination before you spend, because refunding is done one point at a time and costs currency.
Take the travel nodes you need, not the ones that look good
The cheap early constellations exist to unlock affinity of a colour. Taking one for its own bonus, when it does not feed the route, is how people end a playthrough four points short.
Do not save points
An unspent point does nothing. Partial constellations still give their node bonuses, so spending as you go is strictly better than hoarding for a route you may not finish.