First, target the entryways. Whether it's a porch or a doorway, "the area outside your door is a good place to refresh," Gillingham-Ryan says. Some options to get you started: a new mat, some plants or a table with chairs.
If you have a view of your porch from the inside, "it's a great place to set up tables and chairs," he says. "A little cafe-style table and chairs. You can get them in all price points now. Folding bistro chairs are good because you can put them away easily."
Another trick that blurs the line: Use indoor-outdoor fabrics in your living areas inside as well as outside, says Cortney Novogratz, co-host of the TV series "9 By Design," and co-host of the upcoming "Home by Novogratz" on HGTV. Fabrics are available in a host of colors and patterns, including brights, geometrics and stripes.
Her favorites: "I love to go with bright colors: orange, yellow. I'm a big fan of yellow."
One pro secret: Use the same fabric on your deck, terrace or patio and the adjoining room. "Then if you have your door open, everything is one," she says.