If it has been a while since I drew something, I'll often make a reference for myself to remind myself of the basics. This one was done as an example for the giveaway and review I have going, but it's the kind of thing I do. I'm odd that way, lol.
I seldom keep these. Similar drawing references abound on the internet and in books, so the intent isn't to keep them for future use, but get me drawing the subject I'm interested in, and bring back what I already know. If it's a new subject, it's a way to help me keep the information in my head (pun intended, in this case!).
DotPad paper is great for drawing these. I'm not worried about the proportions being perfect, and I don't want to fuss with rulers. The dots get me close enough, and I can count off dots to get my sizes. I could do the same with graph paper, but with all the proportion notations, arrows and directional lines these references get messy. Dots help keep things clean and simple.
I hope I've given you some helpful ideas this week, and good luck to everyone who enters the giveaway!