I have imported the image below as a plane, and am adding lots of vertices to the plane in preparation for dividing it into quads and triangles that are aligned with the contours of the mountain shown.
When going through tutorials, I recall it being said that one should avoid triangles whenever possible. Once I have created all the vertices and start connecting them, dividing up everything into spaces that make sense to stretch vertically and thus form the contours of the mountain, do I need to plan well to avoid triangles? These points are going to be pulled fairly far along the z axis, and then they will need to be proportionally edited and subsurfaced to get the soft shapes of its slopes correct. I wouldn't want patches to start misbehaving once I've gotten to that point. Are there general guidelines about this?