I have to respectfully disagree.
People with average IQs often have far more common sense that people who test better on intelligence examinations.
People with high IQs are often very good at deceiving themselves into believing the most preposterous things.
I still say that life experience and real world responsibilities are the best way to assess a voter's worthiness.
I feel much more confident sending a 25 year old high school grad who works two jobs, pays a mortgage and supports a wife and kid into a voting booth than I feel about a 30 year old Ivy League doctoral student who lives alone in an apartment his parents rent for him so he can study gender theory.
I set that as a base line. I have met to many people who are ignorant and are proud of it. Morons should not vote.