I certainly can plead guilty to many of the "teen offenses" which John writes about -- highly derivative works based on what book I'd just read or whatever movie I'd just seen. Never quite sure how much was a desire to do a better job or just be clever enough to say "See? I can do it, too!"
Plus you don't have to be a teenage writer to get anything of value, or affirmation, from John's piece.
A Few Points
I'd add a couple of things to John's lists. One of the reasons for reading widely is because until you do, not only will your voice be influenced by too few models, making you sound like you're channeling whomever you last read, but because many of your "original ideas" are already out there. This doesn't mean you shouldn't write them -- there are only so many plot possibilities -- just realize that the well-read pro editors in the business are not going to take you on your word that your ideas are so damned unique. Only after reading a lot and seeing your plot ideas in bits and snatches from here and then, and later running into them again, will you realize that you can tell your version of this type of story. Yours is just one voice amongst many.
And cat vacuuming... I've known about cat vacuuming for sometime. As one who sometimes preaches Optimized Procrastination, there are lots of things to do and write in between those sessions where you really get down and write. But if you don't set aside time every day to write, even if you're just blogging (grin), then when you sit down to really write your story, you won't be functionally ready to write, because you won't be used to doing it.
And for goodness sake, don't take the cheap and easy way out. ANYBODY can be a published writer -- if you do it yourself or pay someone to do it for you. Modern word processor software and decent printers, especially laser printers, will give you a nice looking, near-published appearing output. While it is sometimes a good ego boost to see what your stuff looks like when laid out like a magazine story or a novel, don't get seduced by the Dark Side. Make someone pay YOU to publish your work. Taking the self- or vanity publishing option may short circuit any future writing career before it even takes off.
Get Out More
There are scads of local SF/F/H cons to go to. Lots of nice people to talk with. Plenty of decent panel discussions to give you insight on writers and writing, to say nothing of actually meeting some real published authors. Take advantage of these. Afraid to go or your parents won't let you? (In the spirit of John's original blog for teenage writers.) Get some friends and go in a herd. Use the one-day rate. You don't have to get a hotel room and party all night and stay for the whole weekend to get something of value out of a con -- even assuming you had parents foolish enough to let you. (double-grin) Use the Internet and find the program for the con.
Anyway, that's my two cents for today. I'm supposed to be grading papers rather than vacuuming this particular cat...