Some of the best selling books online are adult colouring books. They are not like your typical children's colouring books – which have huge illustrations and are not especially challenging to anybody who has hand-eye coordination and is over the age of 12.
I maintain a digital visual diary in which most days I try to spend some time looking a visual design technique used in all types of medium. I have a subscription to Press Reader which allows me to access hundreds of magazines from around the world. Any design elements that I like I take screenshots and snippets from magazines or websites that I visit.