Kelly Galvin Robson, a Philadelphia-based designer who runs the online shop High Street Market, was the guest for an online Q&A. Here is an edited excerpt.

Q. When looking to invest in a piece of furniture, like a couch, I want something I won't get tired of as my tastes change. What styles and lines do you find to be timeless and work with the most decorating schemes?

A. When investing in a good sofa, you'll want to turn to the classics. You can't go wrong with a good tufted chesterfield, because they're masculine and a little old school.

I like a style that has a strong arm to balance out the fancy tufting. If the chesterfield is too fussy, try something with an English rolled arm. Mitchell Gold has a great option called the London sofa, and it's right on the money. You'll never get sick of it.

Q. Rugs are so expensive, and my house is all hardwood floors. I have young children and need something that is comfortable underfoot, large, able to withstand wear and tear, and won't break the bank. Where should I look? Also, what do you think of layering rugs?

A. Because you still have young children, don't invest in anything precious. Try a large jute rug. They're neutral, softer than a seagrass, and they'll hide dirt and spills. Jute rugs are also pretty inexpensive, and you can find them at any large retailer. Ikea has a great option called the Tarnby.

From there, you can layer it with a smaller, more colorful flat-weave rug. Layering rugs adds instant interest to a room. It's one of my favorite tricks!

Q. My husband and I are buying a farmhouse built in 1921. We ... can't wait to get to work. I want to keep the design simple and true to its roots without looking dated. What are some timeless staples we should start with?

A. First, congratulations! Now, get ready: Home renovations can be challenging, frustrating and time consuming. But it's also rewarding and sometimes even fun.

In terms of choosing materials, get to know the period and style of your home. This is so important. Study popular materials that were used at the time the house was built, paying close attention to lighting fixtures, tile and trim work. These are the elements that you want to shine when the renovation is complete.

The biggest mistakes happen when homeowners choose fixtures that have nothing to do with the original integrity of the house, so stick with the classics. I like Carrera marble, polished nickel, glass doorknobs and hardwood floors. If your home has some unique historic features like pocket doors or built-in cabinetry, show them off!

When choosing furniture, you'll want to incorporate antiques with modern pieces. That way, your home will feel fresh without looking like a museum.

Q. What are your thoughts on marble vs. granite countertops?

A. I'm a huge fan of white marble like Carrera or Calcutta. However, I realize that it's high maintenance and has to be sealed every year to prevent stains. If you're looking at granite, stick with a solid color and a honed finish. Honed granite counters are gorgeous and avoid that speckled look that new construction has.