Not a question, just suggestions

Hey, i saw you dind't use Angle constraints with C, someone at the comments already suggested this.
When i start concepting i also use planes with the knife tool. In addition i also use custom transform orientations (the + mark) to make 30 and 60degrees angle variants, so you don't have to manually rotate along a vertex and having to type in everything.
Plus i use Tiny-CAD addon all the time for these angled-lines. You'll find the VTX|Auto feature very usefull, as it extends 2 edges and generates a vertex to the point where the edges would meet (edges should be allinged on the same axis though).