How to tell if a $1 is real?

Excuse me, could you please elaborate on how one can effectively discern the authenticity of a dollar bill? Is there a specific series of steps or features that one should look for when examining the currency? For instance, are there any particular markings, watermarks, or security features that are unique to genuine dollar bills and can be used to differentiate them from counterfeit ones? Additionally, are there any common mistakes or red flags that individuals should be aware of when evaluating the legitimacy of a dollar bill?