Only one person is opening this email. Remember that. You are not a broadcaster. You are writing to one, individual reader. It’s never “Hey, guys!”
“Don’t call it a newsletter.” It’s a private email list.
What delights me about other personal newsletters: surprises, fun, odd and obscure links, lack of formality, hand-drawn or original/interesting images.
(Also on a meta level I appreciate writing out the philosophy for using each channel.)