Eli Blumenthal

USA TODAY

With Thanksgiving and Black Friday sales upon us, retailers have upped their promotions to lure in shoppers with big “doorbuster” deals on technology. But just because a TV is “4K” or “$500 off” doesn’t necessarily make it a good deal.

Here’s a guide on sorting the studs from the duds on the shopping holiday.

Know what you want to buy-- Don't be fooled by buzz words

Just because something may be on sale doesn't necessarily mean you want it. If your current TV works fine and you aren't buying a 4K game system like a PS4 Pro or Xbox One S, or a streaming device like a Chromecast Ultra or Roku Ultra anytime soon, you don't need to spend money on a 4K TV this weekend. And unless you are buying a 55-inch TV or larger you likely won't even fully appreciate the difference 4K makes.

Black Friday isn't over yet: Get great deals before they run out

If you are in the market for a TV, look for something called HDR, short for high-dynamic range. This will display richer colors, deeper blacks, and brighter whites to make what you see even more realistic. As with 4K, HDR content is still lacking, but it is quickly picking up. The PlayStation 4 and Xbox One S already allow you to play certain games in HDR, with more content coming next year.

Beware of old products

While Black Friday is a great time to buy products at a discount, it is also a great time for manufacturers to clear inventory. Samsung, for instance, is selling a pre-owned Sprint Galaxy Note 3 phone on its site as one of its "Black Friday deals" for $249.99. The Galaxy Note 3 was a great phone-- three years ago. Not only is the phone long out of date but there are plenty of better options at that price point including the Nextbit Robin and Moto G4 Plus. They aren't the most powerful phones, but they are at least modern.

Don't be fooled by some Black Friday 'deals'

If you're willing to spend a little more, you can choose some more powerful options such as the OnePlus 3T, ZTE Axon 7 or LeEco's Le Pro 3, which all retail for under $400.

Know the prices, the actual prices

More than a few of the Black Friday deals advertise big discounts like 25% off a game or $100 off a TV. These sound great, but searching the product you're about to buy may reveal that this deal isn't all that its cracked up to be. Often times the discounts are on the manufacturer's suggested retail price, or the products' original price, and depending on how the item has been sitting on the shelves in or a warehouse, that price may outdated.

There is no denying that every little bit of savings counts, but a quick search could show that it may not be worth buying this product right now.

Look up the products you're about to buy

An $150 TV or an $100 laptop sounds great on its face. But know what you're about to buy.

That $100 computer, a staple at a few Black Friday shops such as Best Buy and Dell, is a basic, low powered machine. The processors aren't great and neither are the screens. Will it do the job for basic web browsing and working on a Word document? Sure, but you'd be better off springing the extra $20 for a Chromebook. Walmart has a Samsung Chromebook 3 for $119 on Black Friday, and we're talking the better performance.

4 things to know before shopping for Black Friday doorbuster deals

Same is true for TVs, phones, video games and appliances. Research the brands, and where possible and model numbers.

Shop around and plan ahead

In today's world, shopping at multiple stores at the same time has never been easier. Before you buy that TV from Best Buy, check out Walmart, Target, Amazon or Costco. A quick glance at the screen on your smartphone could find better deals elsewhere.

It is also important to plan ahead. The touted "doorbuster" deals are often limited, so do your research before the sales start to make sure you know exactly when and where you need to be.

Happy shopping.

Follow Eli Blumenthal on Twitter @eliblumenthal