Watercolor demo but any media may be used. This lesson taught me to just get busy and not overthink things or 'worry' about creating. Starting is the best way to get creative. See what happens when you start simple with no expectations. Believe it or not, these 'humble studies' of a drab scene will help me with my (Part 2 video) large summer marsh painting. Watch this first, and try the assignment... please avoid the temptation of skipping ahead to the 'good stuff' with the large art.
There is no 'perfect scene', so pick any nature subject to sketch... really anything you see out your window... and try to 'make something' of it with these factors: 1) value 2) shape 3) variety 4) separation of near/far or horizontal/vertical plane (such as grassy field and upright trees). Notice I did not say color, this might come later in your final sketch but do not have this as a primary factor. Color is a pitfall as we see in the first demo cube. Work small. Create several studies. Don't have any other goal than to just be present and try this out for about 10-20 minutes. You can copy my demo if this feels better to you, but do try your own scene next. This will be easier if done from life. Photos encourage 'copy this' mentality and we are breaking away from this for our studies. Photos have black shadows, tangent edges, and confusion with so much detail. Photos are not 3-D.