Pronouns should be consistent throughout a sentence. When one starts with a particular pronoun, one should continue to use that pronoun, or a pronoun that is consistent with it, throughout one's whole sentence.
Example: The more you study for the SAT, the more one thinks about moving to Mongolia.
This sentence starts with the pronoun you and then ends with the pronoun one. This is inconsistent. It should be either:
The more you study for the SAT, the more you think about moving to Mongolia.
or:
The more one studies for the SAT, the more one thinks about moving to Mongolia.
Examples for practice:
The more you complain and complain, the more one becomes worn down by one's negativity.
On Tuesdays I drink lattes with lots of caramel syrup, but I worry because you can take in way too much sugar that way.