Black Friday is a big shopping day, but don't rush to swipe your plastic as soon as the doors open on Friday (or Thanksgiving Day). A lot of the deals that seem awesome aren't that good at all, and the ones that are good probably aren't the ones meant to catch your eye.

These rules can help you get through Black Friday with your money and your humanity intact, and still allow for a little Thanksgiving weekend relaxation.

Death to Doorbusters

Doorbuster sales are highly publicized, big discounts for a few specific products, most of which are in limited supply. The idea is they get the crowd clamoring for savings as soon as the doors open. Ignore them. Seriously, put them out of your head, rip the doorbuster pages out of the store circulars, and pretend they don't exist.

You'll recognize the name and possibly even the model of the HDTV/game system/cell phone/tablet on sale, and you'll salivate at the super-low price, but you'll also probably miss the fine print that matters: "Limited quantities." Big stores get a small handful of these deep discount doorbuster items in, and once they're gone (often before the doors open, if the store hands out tickets for the items hours before the sale), they're gone. If you want to camp out in the cold hours before the doors open with hundreds of other equally savings-hungry shoppers for a chance to win the retail lottery, go nuts. But doing so is a sign of madness.

Check the Price Elsewhere

Black Friday deals often look amazing when compared to suggested retail prices, which is almost always how ads describe any discount. Suggested retail prices aren't always applicable outside of Black Friday, though. Lots of products are readily available for well below the manufacturer's suggested retail price (MSRP) regardless of the time of year. You just won't find proof of that in the Black Friday ad.

If a sale looks great, look for the same product elsewhere. Look up other retailers, both online and in physical stores. An HDTV might have a $2,200 MSRP and be on sale for $1,400 on Black Friday, but you could just as easily find it available for $1,500 any other day if you look at another retailer that isn't pushing that model at that price for just that day.

Black Friday ads are designed to make the savings look unbelievable, and they almost always use the MSRP to show just how much you'll save. If you find out you're saving only 10 percent instead of 50 percent, you might think twice about braving the Black Friday crowds to get the gadget you want.

Read Our HDTV Reviews (Even for Different Models)

HDTVs are some of the biggest items on sale on Black Friday, both figuratively and literally. They're also different from big-name cell phones and tablets. You can identify an Xbox One or a Samsung Galaxy S5 easily. But do you know the difference between a Samsung H5203 and a Samsung H6350 HDTV? HDTV manufacturers make many different sizes and models of screens, and not all are created equal. Worse yet, all of these different sizes and models have long names that look like serial numbers. And you might not find a review for the HDTV you're looking for if you Google any part of that name.

Most HDTV models are designated by easily recognized patterns, if you pay attention to those patterns. Look at the screen size of the model on sale and look at the name of the model. Part of that model name will be the screen size. The 60-inch Samsung UN60H7150, for example, has 60 between the UN (meaning LED HDTV) and H (meaning 2014 model) indicating the size of that model. The 7150 is what you need to look at. That number shows the general tier of that HDTV, and whether it's a budget, midrange, or high-end model. Figuring out how every HDTV manufacturer defines those model numbers is a massive headache, but here's a good guideline: Look at our HDTV reviews for the model listed, and find a similar-sounding model with a tier number that's close to the one on sale.

No, it's not the same HDTV, and you shouldn't consider it a definitive review. We test specific models in the lab, and performance can vary between them significantly. But if you find the closest-sounding model we've tested with the closest specifications, you can get a general sense of what sort of HDTV is on sale. Always compare the specs and check if you'll be losing anything from the model on sale (some discounted HDTV models have fewer HDMI ports than ideal, or lack connected features, for example). Still, you can get an idea of what you're in for and whether it's worth the effort to get it on Black Friday. It's also a great way to check if there are any similar models already on sale.

Beware Unnamed Tablet Deals

There might be hundreds of different HDTV models out there, but most of them will be from recognizable brands. That isn't the case with tablets. Many, many Android and Windows tablets come from relatively unknown companies or are simply unbranded, and you can't be sure of what you're getting. If it says Lenovo or Acer or Toshiba, there's a good chance we've reviewed it (and you should check our tablet reviews to make sure). If it just says "Android tablet" and it costs less than dinner for four, there's a good chance it's a piece of junk.

There's a reason iPads, Lenovo Yogas, and Samsung Galaxy Tabs cost much, much more than seemingly similar tablets. Major brands and major models roundly offer better specs, better build quality, and a better experience than unbranded tablets. It's easy to throw around enough components to run some version of Android on a 7- or 10-inch screen. It's hard to make a responsive, well-equipped, well-designed tablet. Even if the specs seem similar, once you look under the hood or hold it in your hands, the difference will become apparent.

This doesn't mean all brand-name tablets are great deals, though. You can still get a mediocre or even downright terrible tablet from a major manufacturer. You can also get a diamond in the rough with a no-name tablet. The problem is you can't know about that unbranded tablet until you put the cash down on it. A relatively inexpensive brand-name tablet like an Nvidia Shield Tablet or an Asus VivoTab Note 8 might cost more than the no-name model, but you can be sure we put them through their paces and are worth your money.

Keep Watching the Stars

Well, asterisks. Keep watching the asterisks. This is especially important for cell phones and tablets, but it can apply to anything.

If a gadget is on sale for a very good price, look around that price for any asterisks (* symbols). This means there are additional terms to go with that very good price, and those terms might make that price seem much less appealing. Asterisk, by the way, is Latin for "strings are attached."

That cell phone on sale? *Requires two-year contract.

That tablet on sale? *Excludes these common variations more likely to be on the shelves.

That game system on sale? *Quantities limited, no rain checks.

The fault, dear shoppers, is not in ourselves, but in those stars.

Keep Black Friday on Friday

Guys, Black Friday is supposed to be the day after Thanksgiving. Thanksgiving is supposed to be a national holiday where family members get together, eat, and enjoy each others' company while vaguely paying attention to football games. At the very least, it's supposed to be a day off for most Americans.

Some major retailers are starting Black Friday early, as in on Thanksgiving. Some stores' doors will open just as the sun goes down on Thursday, and hordes of consumers will be invited to descend upon them with ravenous hunger meant to bleed and spread from Black Friday itself. And many people who work at those retailers will be working on that Thursday.

The entire month after Thanksgiving is a festival of buying things, and Black Friday is supposed to kick it off. Thanksgiving is supposed to be a day off, to be with our loved ones and relax under a pile of too much food. Do we really need an extra few hours' head start on Thursday to start getting stuff? Is that important enough to keep big box stores open and their many employees on-hand instead of with their own families for the day? Why does Thanksgiving dinner have to be cut short for the very people who will be swarmed by crowds of crazed shoppers the next day? We should not encourage Black Friday bleed-over into Thanksgiving itself. Take the day off from shopping, and give a day off to the people who are going to sell you stuff tomorrow.

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