How many mistakes did you make yesterday, and how many will you make for the next four weeks? Farhad Manjoo has at least six mistakes he’s ready to warn you about, particularly regarding what you shouldn’t buy for loved ones.

Remember, retailers are counting on your irrationality—the whole point of a “doorbuster” sale is to get you into the store to seduce you to spend cash on more profitable items. So, check your shopping cart before you check out. Ask yourself: Do I really need this contoured lap desk, or am I just buying it because it’s half off?

Among his suggestions of what not to buy:

1. “Blu-ray players”
2. “TVs that are too big, or too fancy”
3. “Extended warranties”
4. “Photo printers”
5. “Digital picture frames”
6. “FM iPod transmitters”

And he’s got good reasons for suggesting as much.