Some visual design techniques don’t belong to layout, typography, or colour. These are techniques to polish the design. They improve the visual design, but aren’t necessary.
I call these techniques “polish”, like shoe polish.
Whatever you call them, there are common techniques used to polish designs. Look at lots of good visual design and you will start to see techniques repeated.
One reason it’s important to look for these techniques is that visual designers often don’t talk about them. They’re happy to talk about layout, typography, and colour. But they forget all of these other techniques they use to make good visual design.
This annoys me so I’ve collected every polish technique I’ve come across.
Many of these techniques are trendy. Colourful drop shadows were popular for half a year. Now they’re less so. It’s still a good idea to be familiar with trends like these. One day you might need to design something fashionable.