I may not be able to post tomorrow, so have another glitch today:
Need to know when to capitalize mom/mommy and when not to? It’s simple: This is my mom; I call her Mom. Capitalize when used as a proper name; don’t capitalize otherwise. (This is why sister isn’t capitalized unless you’re referring to, say, a nun: My sister became a nun, and now everyone calls her Sister Margaret.)
Apostrophes do not make plurals, but they are needed for possessives.
A compound sentence is still a compound sentence when the conjunction is something other than and — or, for example. It needs a comma before the conjunction (yes, even if you already used one).
“I have a secret, but I can’t tell you, or the thing wearing Mommy’s skin will get mad.”