Text: the six strings of a guitar is called "a set of strings".

Correct capitalization: The six strings of a guitar is called "a set of strings".

Text: when i turned the boat to run with the wind, i had taken the mainsail down and secured it to the boom and ran nicely with the wind for a couple of rounds of the rolling foresail.

Correct capitalization: When I turned the boat to run with the wind, I had taken the mainsail down and secured it to the boom and ran nicely with the wind for a couple of rounds of the rolling foresail.

Text: no processed food. i use an infrared sauna three times a week to improve my circulation.

Correct capitalization: No processed food. I use an infrared sauna three times a week to improve my circulation.

Text: scattered hotels don't call for new construction, but rather, for the restoration and preservation of centuries-old architecture, reconverting an existing room into a hotel room is far more sustainable than building a new hotel.

Correct capitalization:
Scattered hotels don't call for new construction, but rather, for the restoration and preservation of centuries-old architecture, reconverting an existing room into a hotel room is far more sustainable than building a new hotel.