Random grammar advice from a tech writer and editor

Hi! Tech writer and editor here. My day job is ensuring that blog posts authored by technical folks are clear, easy to follow, and accessible to everyone. I’m feeling feisty today, so here is some unsolicited, nit-picky random grammar and writing advice for you.

1. Never use an ellipsis. There's a 95% chance you're using it wrong, so just use a period and be done with it.
2. If you don’t know how to use a semicolon, just use a period and then start a new sentence. In fact, it’s probably a good idea to use a period and start a new sentence, anyway.
3. Don’t use parentheses if you’re over 40. You’re gonna forget to close them. Actually, don’t use them under 40, either.
4. Using “and more” at the end of a series instantly turns your post into a marketing piece rather than an educational one. Remove the “and more” and just add a period after the last item.
5. Ditto with “etc.” It just makes you look like you forgot the rest of the list. The readers can extrapolate if they want.
6. Keep bulleted or numbered lists to seven items max.
7. Huge blocks of text are hard to read. Use sub headers to break it up and help guide the reader through your thought process.
8. Yes, the whole tell-‘em-what-you’re-gonna-tell-‘em, tell-‘em, and tell-‘em-what-you-told-‘em still applies.
9. Don’t use an em dash when a comma will do, unless you really want to be a drama queen about it.

There is more, but that's enough for now.