One of my best friends works as an interior designer previously in Chicago, now in Austin Texas.

He asked me to come photograph an apartment he had designed for his website.

1ST and most important go get yourself a good tripod. Most of these photos are taken on a slow shutter speed. a tripod and a remote control for the shutter will help minimize camera shake
2ND I highly suggest renting a wide angle lens if you don't have one. I shoot Nikon and love my 24-70mm but any wide angle lens will work. If you don't have one and don't wanna spring for one then grab your 50mm and use that
3RD details details details. Make sure you have a great portrait lens for jumping in there and showcasing the details of each set. Again I am Nikon I shoot a D800 and found my Nikkor 85mm lens perfect for this small interior space
4TH if you have time try and shoot at several times of the day to catch multiple exposures of the sky. You can combine 2 photos into 1 by bringing a sunset or twilight sky to a beautifully lit interior.

5TH most important tip.... Get a list of who sold your clients their items on display and furniture then tag them on your blogs and social media. You will be surprised how many people who follow them start following YOU!!