One aspect that was tricky were the colour palettes required; I had to develop several palettes for different types of maps and charts, sometimes with as many as 25 colours. There were several different things to take into account: contrast in colours from each other; contrast in light and dark to help those with colour blindness; contrast to ensure colours are distinct when placed next to other colours on a map; stepped shades; correlation to positive/negative or high/low.
I had to let go of the desire to create aesthetically pleasing colour palettes, as the requirement for as many different colours, as well as wanting to create high contrast, sometimes resulted in uglier colours, but ensuring all of the data was clear was the priority, and I learnt that sometimes a design doesn't need to be flashy or pretty to do its job.
