Is there anybody who knows the proper method to end a letter? If you have something useful in your mind. please mention it.

Here is what I know. Whenever I write e-mail to my foreign friends, I write 'best'.

For example,

Hi, Aaron. How have you been? It's been a long time since we met last time. Are you hanging out with friends who I introduced to you? They are cool, aren't they? (After other gossips)

Best,

Andy.