People like to put together lists of rules for making better visualisations. In the published literature, I can find a couple of good examples. Rougier et al. (2014) offers some high level advice and Keheller & Wagener (2011) some slightly lower level (more practical/detailed) tips.
As a bonus, I quite enjoyed this top ten worst graphs in the scientific literature.
UPDATE: On reflection, I think I can boil all these rules down to two meta-rules 1) Know your message 2) Don’t lie.