In is often incorrectly used for into; as, “He hurried up the street and rushed in the store.” We walk in a room when the walking is wholly within the apartment; we walk into a room when we enter it from some other room or from the outside.
Just going to
“I was just going to write you a letter.” Say “I was just about to write you a letter.”
Kind of
“James swallowed the dose, and now feels kind of sick.” Use slightly or somewhat, or some other modifier, instead of kind of.
Knowing
Do not use knowing for skilful or intelligent. “He is a knowing artist.” “See him prick up his ears; he is a knowing cur.”
Clever, Smart
In England the word clever is applied to one who is bright, intelligent, ready, apt; in the United States it is often misapplied to one who is good-natured, kind, or accommodating.