Home improvement is one of the most rewarding responsibilities that comes with homeownership. It can also be a big financial investment, so it’s important to make smart decisions about which projects to take on and which to leave for the professionals.

Some home improvements are just can’t-wait tasks, such as fixing a roof leak or replacing worn doorknobs. But a little planning can help you avoid making costly mistakes that could hurt your home’s resale value or cost more than they’ll pay off.

If you’re not skilled in electrical work, plumbing or installing heat systems, it’s best to hire pros to get the job done safely and correctly. In addition to the obvious safety reasons, relying on qualified workers will usually yield better results and potentially save you money in the long run.

Depending on the scope of the project, it can be difficult to estimate how much it will cost. Generally, homeowners should stick to the budget they set for themselves and be sure to factor in hidden costs, such as unexpected problems with materials or labor. Getting bids from several contractors is recommended.

When it comes to financing home improvement projects, 3 in 5 homeowners say they’re “easily able” to pay for the majority of their projects without tapping into savings or going into debt, according to a September NerdWallet survey. Other common sources of funding include cash-out refinancing, a home equity loan or line of credit (HELOC), contractor-arranged financing and credit cards.

Homeowners are spending more on home repair and improvement projects than ever, a NerdWallet analysis of Census Bureau data shows. The typical American homeowner spent $522 billion on these projects in 2019, up $72 billion from the previous two-year period.

While it’s tempting to spend more on high-end upgrades, they’re not always worth the extra cost. It’s best to focus on midrange improvements that are likely to appeal to the widest range of potential buyers. For example, converting a garage into a living space may increase the size of your house, but it’s unlikely to add as much value as adding an additional bedroom or bathroom.

It’s also important to keep in mind that overly customized renovations can be less appealing to a future buyer, which could lower your home’s resale price. Be sure to discuss any major renovations with a real estate professional in your area to see how they might affect your home’s resale potential. And don’t forget to put any agreements in writing, especially those involving repairs and a timeline for completion. That way, if the project goes over budget or takes longer than expected, you’ll have documentation to fall back on.