The biggest mistakes people make when flipping a house, according to an expert

• Home renovations can be complicated, and it's easy to make mistakes along the way.
• Tamara Day is an interior designer and the host of HGTV's "Bargain Mansions," and she's flipped 14 houses this year.
• Day said that it's better to invest money in long-term fixes even if they cost more money upfront — and that if you're going to flip a house, you shouldn't buy a home at the top of your budget.
• The new season of "Bargain Mansions" premieres at 8 p.m. ET on Monday on HGTV.

There are many reasons to renovate a home, but the process can become a bit more complicated when you're preparing to sell or flip it.

It's not always easy to know what's worth spending your money on, especially if you want to make a profit on the sale.

Insider spoke with Tamara Day, an interior designer and the host of HGTV's "Bargain Mansions," about the biggest mistakes people make when flipping homes or preparing their homes to go on the market.

Day has flipped 14 houses so far this year, and many of them will be featured on the new season of "Bargain Mansions," which airs on Monday.

Making affordable cosmetic fixes can pose problems in the long term

Sellers often know they need additions like stone countertops and hardwood floors to sell their houses, but they don't always want to shell out the money for the nicest materials, Day told Insider.

"They just go and buy the most basic granite and the most basic hardwoods and the most basic carpets," Day said of homeowners and sellers. "But that's not what people are actually looking for."

Instead, Day said that homeowners should spend more money on cosmetic updates up front so the home is easier to sell.

According to Day, buyers are "not looking for basic, they're looking for beautiful."

"I think it's throwing good money away to pick something based on price, not based on style and what the potential buyer is looking for," she said.

If you're buying a house to flip, don't always go for the nicest option

It may sound counterintuitive, but when you're planning to flip a house for profit, Day said that it doesn't always make the most sense to buy the nicest house you can get in your budget.

"When I look at a house, the uglier it is, the better it is," Day said, adding that the lower the price, the bigger margin there is to make renovations.

"At the end of the day, if you buy a house that is kind of fixed up and you're paying a little bit more for it, and you're still ripping out the cabinets and you're still ripping out the countertops, you've paid a little bit extra for just OK," Day said.

She suggested that homeowners and sellers consider the fact that they will likely pay the same amount of money to fix up the cabinets in a home that's in worse condition.

"You're putting your money toward something that really is improving the value of the house," she explained.

Hiring an interior designer for a home renovation is often overlooked

Whether you're flipping a house or preparing your own home to be sold, you'll want to use your money as effectively as possible.

Day pointed out that interior designers can help owners make the most of their budget, so they should be considered a resource rather than an expense.

Plus, interior designers can help owners avoid major home decor mishaps, Day said.

"Hiring somebody that knows the trends and knows the styles can help you save a lot of money," Day said. "If you pick the wrong granite — you put it in, and you hate it, and it's not adding value to your home — that was a huge cost that didn't have to be spent."

The new season of "Bargain Mansions" premieres on HGTV at 8 p.m. ET on Monday. You can also follow Day on Instagram.

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