Approach upgrades by bottleneck
Prioritize the kind of improvement that addresses the obstacle in front of you: wave clear when progress is slow, or resource and progression improvements when you are waiting on an unlock. Test a small set of changes before spreading resources across unrelated branches.
Keep choices connected
The skill tree works alongside equipment, jobs, crafting, and gathering. A useful choice supports the setup you actually use, rather than simply the most recently unlocked option.
What this page will not claim
Without verified in-game evidence, a fixed best route would be made up. A future node-by-node map can be added here when documented screenshots or official information are available.