Buying a mattress online is very easy. But if you are too careless in your search for the best mattress, you could end up with a bed that is not at all to your liking. We don't want that to happen, so I'd like to offer my advice as a professional mattress tester and deal hunter who has been covering Black Friday sales for the past 15 years.

Below are my three golden rules for winning this year's Black Friday mattress sale. This is advice worth following at any time of year, especially since mattress sales take place all year round. If you're looking for more information on a particular model, we have a huge library of reviews, so be sure to take a look.

Buying a mattress without seeing it may seem risky, but to ease shoppers' minds, reputable sleep companies offer at least a 30-day trial period. The average mattress trial period is 100 nights, but some, like Nectar Sleep and Saatva, offer trial periods of up to one year to test the sleeping comfort before making a final decision.

Be aware that not all mattress trials are risk-free. Some may not accept returns unless you can provide proof that you have donated the mattress to a local charity. Also, they may not accept a return unless you can prove that you donated the mattress to a local charity.

Final sale and clearance items are often exempt from returns. Final sale and clearance items are often exempt from returns and generally do not come with a trial version.

As with other big-ticket items, it is wise to browse various retailers to find the best mattress deal. Most brands of hybrid and memory foam mattresses can be purchased from at least one third-party store, usually Amazon.

Nevertheless, it is strongly recommended to buy directly from the brand whenever possible to ensure the best aftercare. For example, Nectar offers a one-year trial and lifetime warranty when purchased directly, but only a 120-night trial and 10-year warranty are available when purchasing Nectar from Mattress Firm.

Keep in mind that a few mattress brands, especially luxury mattresses, are not sold elsewhere; Saatva and WinkBed make their beds to order and deliver them flat (as opposed to a boxed bed).

There is a misconception that price is the most important factor when buying a new mattress. Nor should you skimp on something that will make you uncomfortable in the long run.

What you should always do is know up front what features are most important to you and narrow your search from there. Before buying a new mattress, ask yourself:

Evaluating your sleeping needs and preferences will help you avoid buying the wrong type of bed. Of course, you can (hopefully) try it out, but returning a mattress can be a hassle and you're back to square one.

An honest evaluation will help you find something that will take you straight to dreamland every night. If it didn't work the first time, but you just want a little extra comfort, buy a mattress topper. In most cases, it's much cheaper than returning the mattress and buying a new one.