The other confusing warranty issue is the appealing-sounding lifetime warranty. You probably assumed "lifetime" means your lifetime, right? Not always. There's no set legal definition of "lifetime warranty."
Some weaselly companies choose to interpret it as the lifetime of the product. I know, it's ridiculous. That's like saying, "this product is warranted to last as long as it lasts."
Companies that do it this way set an amount of time that they think their product should reasonably last. If your item breaks during that time, they'll repair or replace it. If it breaks later, you're out of luck.
I have this soft-sided leather briefcase that I absolutely love. I've had it for 10 years -- or at least one like it. I've had it replaced twice. Once, the strap broke under the massive weight of my files. The second time, the stitching unraveled ... under the massive weight of my files. Both times, the manufacturer came through for me. And that's lucky, because a "lifetime warranty" is only as good as the company backing it.
If you're buying something really expensive, you might want to contact company officials and ask them how they define the word "lifetime."
Save the receipt and file it with your warranty in case you later need to prove when you bought the item or that you're the original purchaser.
Don't bother sending in the warranty postcard -- unless you want to. The manufacturer's just fishing for names for its mailing list and you're covered whether you send it in or not.
Perform any maintenance or inspections required by the warranty so you don't void it.
Before purchasing an extended warranty, find out the name of the company offering it and do a background check with the Better Business Bureau.
Your county or state consumer protection office may be able to help. In extreme cases, you could file a lawsuit citing the Magnuson-Moss act, which is the law that governs warranties.