A light fixture is important but equally important is the bulb inside. I love Simply Conserve LED 9W Dimmable Lightbulb . They have the perfect color light which is not too yellow or too blue. I also make sure that all the bulbs in a room are the same so the light is even.
Area Rugs (the right size)
Area rugs make a huge difference in defining a space. The moment a rug goes down the space is already half way to being designed. I find Emily Henderson's advise on choosing the right sized rug very helpful. I have learned that bigger is always better and have felt like each of the rugs I've bought for our home could have been one foot bigger all around (that includes the rug in the Breakfast Nook. Could be a tiny bit bigger). Lesson learned.
Art (original if possible)
Choosing art for a space is one of my all-time favorite things to making a big difference in a space. I have collected lots of beloved pieces over the years and enjoy choosing each one for just the right space in our home. I also love moving them around for a whole new look each season. I've talked a lot about art in the Art and Memory series here on Goss House. ( see Art and Memory, #2, #3, #4, and #5 ) I know buying original art is perhaps daunting, but sites like Minted. Mammoth and Limited by Sach Art are going a long way toward bridging the gap.
(Photo above is a bird drawing/watercolr I did for Helen's Nursery in Boston)