I posted how to draw Atari and a reference chart. Also I posted goods that it would be useful if there was such a tool.

To draw the image of the landscape roughly on the transparent board is a bit of training,
you will need training until you get used to it.
It is basically to make thin horizontal lines of the frame meet horizon of the landscape and to align
the vertical lines vertically, but it is very difficult for trees without buildings etc.
However, horizontal and vertical is a natural way to understand as a human sense.

Set the frame to the composition you want to draw.
Using Board Marker, draw contours only for the things you want to draw, draw quickly with one eye closed as you continue drawing.
Waste, if you draw while correcting it will be extra deviated. Let's dare draw with one line, without hesitation!水彩スケッチツール