How do I convert from tris to Quads?
With Alt + J in edit mode
It also might be a symptom of edgeloops that need to be worked on a reorganized. In other modelers that feature N-gons (or polygons with more than 4 points) it is a bit easier because you can just tessalate yourself a new loop and then delete the undesired points later on.
With blender instead you have to use the knife tool and merge vertex.Which requires strategy and practice I feel.