Usually I take a sketchbook wherever I go. As we're all going a lot less just now let's try sketching from our windows at home.
I've set up a YouTube Channel. In this first upload I I show pencils and pens (expensive artist drawing pens and cheap biros) on paper. Use any materials you want though. The back or inside of envelopes and the inside of food packets are a good supply of free stuff to draw on.
The artists I mention are Winifred Nicholson and Sylvia Wishart. Look at their window paintings. My Art Ideas! - Window Views blog post shows their work and mine and others and has various ideas to try. The book I recommend is Alwyn Crawshaw's Learn To Sketch in the Collins Learn To Paint series. Readily available secondhand on Abebooks.