How to start a Sketch / Painting : Tips for beginning

When I start a Picture , what ever medium , in this case Pencil, I find it easier to work from Photographs, I look at the edges of the photo and work from key points , such as the horizon line, ( where does that come down to , in relation to the page ….a 5th? or a 1/4 , then i move to the far distance landscape… where does that come down to and stretch over using the edge and top of the page …a 1/4 down & more than 1/2 over?
and when you have drawn up your sketch or canvas, move on to the detail, giving rough suggestions of texture, use different directions for the strokes, after start shading, i find it easy to squint at my photo and the shading stands out more prominently and this also works with the high lights, ( it fools your eye into obliterating the off putting details , that you will have to put in later, but is much easier to put in once you have your light source direction).
Writing notes to yourself also reminds you of key areas or colouring to observe.
Good Luck