* The more artifacts you find and trade for, the more it narrows down search areas for uncharted ruins. It's better than just blindly wandering around in a search area half the size of the known nebula.
* Going to the <div class="spoiler">Unknown Extremely Ancient Site</
a> is the point of no return, and the game will not warn you of this.
* The main story's pretty nonlinear, but there are branching paths to a degree that can shut you out of subplots, or at least their best endings. Consider what's best for some people when you decide where to take them, there are better options than Elboreth.