The key question is always the counterfactual one: how likely is this pattern if nothing systematic is going on? If plain random data would throw up the same 'pattern' often enough, the pattern carries no information. Untrained intuition badly underweights how often chance produces streaks and clusters that look far too neat to be accidental.
A few traps deserve names. Apophenia is seeing meaning in noise: faces in clouds, plots in coincidences. The Texas sharpshooter fallacy finds a cluster in random data and then draws the target around it. The advanced routine: state what random data would look like, ask whether your pattern would be surprising against that, find the simplest rule, and ask what data would prove it wrong. For more, see Scientific Thinking.