Today’s second glitch:
Always capitalize the first word of a sentence.
Use a comma to separate a direct address from the rest of the sentence. If it falls somewhere in the middle of the sentence, you need a comma before it and a comma after it. (Obviously, you only need a comma after it if it’s the first word.) In this example, dear is used as a direct address; it’s what the speaker is calling the person to whom she’s speaking.
There’s a comma splice (where two sentences are run together with a comma) after dear. Replace that comma with a period and capitalize Now.
“Mother knows best, dear. Now put the flamethrower in the trunk.”