Despite the best efforts of William Safire, Edwin Newman, and John Simon (surely you've read all of their language-centric books), certain irksome phrases have somehow entered common parlance, like black mold in your shower caulking. They may initially seem innocuous, but if you start paying close attention, their redundancy begins to reek. Once you become conscious of these discordant word combinations, you want to scrub them out of the language forever. Let's examine five such examples and then, if all goes according to plan, never speak of—or use—them again in writing or speech.
1. young teen: You mean as opposed to an old teen? Yeah, that makes a lot of sense. Teen suffices. Teen is lousy with that young stuff. Remember the white '90s hiphop group, Young Black Teenagers? Their music was pretty tight (thanks, Hank Shocklee), but oy, that name—a disaster on two levels.
2. free gift: As opposed to gifts that cost you money? By definition, a gift is free; this is a concept that should be burned into your brain shortly after you learn how to talk. "Free gift" recurs in the marketing world with noxious frequency, because back in the Dark Ages, some advertising genius thought the word "free"—no matter how loosely deployed—would unlock the secret to consumer contentment. But you, you're too smart to use it yourself. Right? Right.
3. past history: Are you one of those people who has a future history? Whoa, how'd you manage that? Jealous! It should go without saying (facetious callback!), but this requires periodic reminders: History is something that has happened before the present. Delete "past" for a better future.
4. advance warning: All warnings are by their very nature advance. If you're warning somebody about something that's already transpired, you fucked up, amigo. And now you have a big mess to clean up.
5. first introduced: If you've been introduced to something for a second time, you have entered into another dimension where the laws of physics (and language) have become folly. Take it away, internet dictionary...