Brief Doodle created in Sketch ClubThe sketching phase of painting (digital or physical) is an essential kicking off point unless you're an absolute visionary master. For the rest of us who are learning the ropes or just need to feel the canvas about, we need to pencil in the basic idea of the image or to even get an image if we're dealing with a lack of inspiration. This piece of advice works for most advanced apps that offer an opacity level for brushes.
So we start off with a blank canvas, the tools surrounding the screen and the stylus is ready for our input. But where do we start? What do I draw? It doesn't hurt to doodle and to play about with lines. However choosing the brush is the first essential step you must take but even that can be daunting with the sheer amount of possibilities in any given app. Let me make it a little easier to decide. Some apps offer a pencil brush that replicate the gruffness of graphite and can be altered to be thicker, darker and even a different color. This is a safe option to take and well advised especially with how great an effect it delivers (especially when used with the smudge tool later.)
Present in most graphic apps, Sketch Club excels in this department with its wide range of pen nibs. It's also worth noting that using red or blue makes it easier to trace over later (or you can just turn down the opacity of that particular layer.)
The route I like to take is using a pen nib and turning down the opacity to 60%-70%. I found using a brush at full opacity in any color delivered a form of finality to the lines which felt daunting. On the other hand it also created a jumbled blob of black or grey, the colors I tend to sketch with. Turning down the opacity makes the lines less certain and creates a sketch or doodle effect even if the lines look incredibly smooth. From these strokes I find a path I'd like to go in and draw over and over in that direction until it darkens enough, slowly creating an image piece by piece.