At one point or another, every homeowner needs to apply a fresh coat of paint to their home’s interior. But just when to do it, how to do it and whether to do it yourself can be unclear. Then, when you add unknowns like cost and color, things can get really confusing. Fortunately, there are some guidelines to follow.

HOW OFTEN SHOULD YOU PAINT?

When you should paint your walls — and include painting projects in your annual home improvement budget — depends chiefly on four factors:

Frequency of use: The rooms where we are most active will need a fresh coat every three to four years. Kitchens, bathrooms, hallways, laundry rooms and mud rooms are on this list. Bedrooms, living rooms and dining rooms, on the other hand, can usually go five to seven years without a new coat.

Wear and tear: Damage from furniture or rambunctious pets can shorten the life of a paint job. If you’re struggling to keep the walls pristine, consider painting them with washable products. If you need drywall repairs before you paint, factor in a repair kit for $10-$30 or professional drywall repair for $60-$90 per hour.

Quality of paint: Quality plays a big part in the longevity of your paint. If you use a high-quality product and primer, you can get almost twice the life you’d get with a low-quality product.

Change of pace: Whether your current color scheme is dated or you’re simply switching things up, sometimes the best determining factor is your taste. If you want a change, then it’s time to paint.

WHAT PAINT SHOULD YOU CHOOSE?

Even if you’re just repainting a wall the same color, picking the right paint is important. Paint technology continues to improve, and you may be able to find a better performing product for your needs.

Color: Color is largely a personal decision. But experts typically suggest the following:

Kitchens, laundry rooms and bathrooms should be painted clean, refreshing colors like warm neutrals, whites, grays and blues.

Bedrooms are best painted in calm and soothing colors like blue, purple and green. Avoid oranges and yellows.

Living rooms can be either energized or relaxed, so a range of colors like red, yellow, pink and purple can thrive here.

Finish: It’s best to consult with a painting expert as you navigate your finish options, but here are the basic rules of thumb:

Flat and matte — Low gloss and tough to clean. Use in low-traffic areas.

Satin and eggshell — Slight gloss and easier to clean. Use in living rooms and bedrooms.

Semi-gloss — Around 50 percent gloss, easy to clean and more resistant to moisture. Use in kitchens and bathrooms.

Gloss — Reflective and shows imperfections easily. Use on trim, doors and cabinets.

HOW MUCH WILL IT COST?

The cost of your interior painting project will depend on several factors: the type of paint, the number of rooms and whether you decide to do it yourself or hire a professional, to name a few. Having an average-sized room professionally painted costs around $400-$800, according to HomeAdvisor’s True Cost Guide, and homeowners typically spend around $2,000 to have their entire home interior painted. Having a single bathroom painted could cost as little as $300, while painting a kitchen could cost over $1,000.

Interior painting can be a DIY project if you put in the time to do it right. The only direct costs will be tools, paint and various necessities like ladders and tarps. On average, homeowners pay $200 to $300 to paint a single room themselves.