Answer:
Hey!
So to start off: we have to address the person in the best and most polite way possible...(for example Dear Sir/Madam OR BETTER EVEN if you know the person, address them by their full name *first name/surname*)
To end the letter the phrases: Sincerely, Regards and Yours Sincerely (FORMAL) and Best Regards, Cordially, and Yours Respectfully (INFORMAL) are the best ways!!
Explanation:
I HOPE THIS HELPS!!