Indoor photography is perhaps one of the most challenging places to shoot for new and experienced photographers. Natural and artificial light combined with natural light reflecting and refracting through windows and off walls can lead to some funky photographs. Mastering indoor photography can be one of the most frustrating things to learn. These seven deadly sins of indoor photography should be avoided, doing so will result in far better photographs.
Lack of Custom White Balance. I've already shown you how and why you need to manually set your white balance, why not take the time to do it? Because almost all indoor photography has some sort of mixed lighting situation, it's almost positive that auto or one the presets available on your camera won't give you great results.
On Camera Flash. Utilizing the on camera flash for indoor photography will surely give you a washed out, unflattering photograph. Avoid it at all costs if you can, even if you need to raise the ISO, avoid on camera flash whenever possible.
Composition is Everything. Because indoor photography consists of so many architectural lines, keeping good composition is of the utmost importance. Really pay attention to how you frame images, especially in places that have exposed brick or tile work. Maintaining a nice, constant flow through the images is essential and even slightly off balanced it will be noticed.
Pay Attention to the Small Details. It doesn't matter if you're shooting friends over for a dinner party or a paid architecture gig, the small details matter! Look at the counter tops for pens and notepaper, do they belong in the shot or can they be stashed somewhere else? The toilet seat cover being down probably looks more attractive, and taking the time to even out towels on a rack will provide a better photo. If there are dirty dishes in a sink, clean and put them away. Full ashtrays look gross and crooked picture frames can make properly composed photographs look crooked. Take the time to stage your photograph, these are things that can't be easily edited in post production.
Bounce the Flash. If you must use a flash inside, use a hotshoe mounted flash, not the pop-up on-camera one. I'd also strongly suggest a flash bracket to get the flash further away from the lens and reduce red-eye. Bounce the flash off a wall, ceiling or, if none are available, utilize an Omni-Bounce or similar diffuser. When you bounce or diffuse a flash, be aware that you essentially lose some of the effective power of it. You'll need to utilize either exposure compensation on your camera or adjust the ISO slightly higher to compensate for the difference. Flash photography indoors should only be utilized when you can't achieve the desired look from natural light.
Windows, Picture Frames, Mirrors and Glass Cabinets. Perhaps one of the most frustrating things to deal with while shooting indoor photography are reflective materials, especially when shooting with a flash. Avoid using your flash if there is glass or reflective materials in the room at all. Pack a circular polarizer filter to deal with the reflective and glass objects in your shots, and be aware you could lose 1/2 to 2 full stops of light, so adjust accordingly either via opening up the aperture or bumping the ISO higher. Also take note to whether or not you show up in the reflection of any shiny objects!
A Tripod is Your Friend! While I know it's nearly impossible to shoot candid photos of people with a tripod, if you're doing architectural shots or photos of non-moving subject matter indoors, utilize a tripod. Not only will it allow you to utilize the lowest possible ISO for the least amount of digital noise, it will provide a solid platform for you to properly align and compose your photograph.
As mentioned, indoor photography is a bit tricky and a lot of people can give up on it quickly. I strongly suggest that you continue to experiment and take several shots of everything, also known as bracket shooting. This will give you a better idea of what is and isn't working for you. One tip worth mentioning that is often overlooked is knowing the time of day and current weather outside, and how that relates to the house or building you're shooting in. For example, shooting in an eastern facing kitchen at 9am is going to provide some pretty bright light through the windows on a cloud free day. The same kitchen at 4pm will probably be much darker since the sun will be passing over the house to the other side and shadows will be far less harsh.