While creating the first low poly pic, I learned...

1. The sequence of creating a low poly should not be drawing triangle by triangle. The best example is here: https://www.behance.net/wip/696463/1270451 It's better to sketch first according to the color and shade, and then fill in the triangles.

2. Don't be afraid of being too detailed or too general. The sizes of triangles can be very different, to have a dramatic feeing.

3. Avoid slim triangles, unless you have good reasons. Big triangles with two long sides and a short side just look wrong. Triangles with balanced sides work much better.