While Black Friday may not be as important as it once was, it still marks the opening of the holiday shopping season. With retailers desperately trying to get customers in the door, it can be one of the best times to scoop up certain big-ticket items.

For some items, though, you're better off buying at other times during the year. There are always exceptions, but in most cases, these are the items you should not buy on Black Friday, and instead wait until the perfect time of year to snap them up.

People carry colorful shopping bags.

Black Friday is the traditional start to the holiday shopping season. Image source: Getty Images.

Grills

The peak deals on grills actually happen in October when retailers look to clear space for cold weather merchandise. That makes sense because grilling season, at least in part of the country where it gets cold, tends to run from Spring through the middle of fall.

With few people looking to buy grills as temperatures call, most retailers trim their stock dramatically by September. If you want a grill, the peak deal season has passed, but you may be able to find a steal if a retailer has any stock left.

Christmas decorations

While the best day to buy Christmas decorations is generally December 26, that advice won't really help you if you're looking to deck the halls for your 2017 celebration.

If you're planning to decorate your house or need more ornaments for your tree, dollar stores and other discounters tend to be well-stocked on these items. Consumers can also take advantage of some Black Friday promos to workaround paying full-price for holiday merchandise at some retailers. For example, Target (TGT -0.36%) is offering Black Friday customers that spend $50 in stores or on Target.com a coupon for 20% off a future shopping visit, valid November 28 to December 10. Shoppers can buy everyday items on Black Friday to hit the $50, then use the discount on a future purchase to get the seasonal items they have their eyes on.

Mattresses

The holiday season is not the best time to buy a mattress. That would generally be in May, according to Cheapism.com, due to the new product cycle in the mattress industry. Since mattresses aren't like cars and most people don't care if they have the latest model, consumers can often take advantage of retailers needing to free up space for new inventory and get good deals in the spring.

During the holiday season, your best bets on mattresses are generally stores offering large overall discounts. One good choice -- if you're not worried about the chain being around for returns after the holidays -- is Sears (SHLDQ).The struggling retailer has already started its holiday sales and is offering deep discounts (up to 50% off) on everything in its stores including mattresses.

Gym memberships

The fourth and first quarters are the busy season for gyms. People are joining either to fulfill New Year's resolutions or out of guilt over how much they ate. Because of that steady demand, you're not likely to get much of a deal whether you sign up now or in the middle of January. 

Gyms offer the best deals in summer because that's the season where not only fewer people are joining, but many existing members are staying away. That lack of foot traffic costs the fitness clubs incidental revenue as fewer people coming in means less money spent on water, snacks, and apparel at the gym.

If you are eyeing a new gym membership in the next few months, it's also important to remember that many gyms can be open to negotiation.

By simply researching prices for local gyms and speaking with staff, you may be able to get a slight discount or have certain fees waived

Of course, if you want that deal, you may have to be flexible. That could mean paying for a year upfront or agreeing to pay via automatic withdrawals from a bank account.

It never hurts to try

While these items should generally be purchased at other times of the year, shoppers can still find deals on all these products during the holidays by doing their homework. One trick that takes seconds, but could save hundreds, is simply researching prices over the past 12 months and seeing if stores are willing to match that price. In addition, watch for unexpected deals which can pop up when retailers have extra inventory (or if they get desperate).