Most single family homes have a half bath on the first floor of the house and sometimes on the second floor or in the basement as well.At risk of stating the obvious, it is important to focus more on the sink and mirror than the toilet. Oftentimes the toilet will be opposite the sink and won't fit in the picture frame anyway. However if it isn't frame make sure the lid is closed. Oftentimes you'll have to place your camera at the fulcrum of the door to get as much of the space in frame as possible. This is important for half baths especially because they are often small and hard to capture. Try to avoid including the cameras reflection in the mirror. Sometimes this is unavoidable though, so in this case have mercy on the editors and duck your head and arms out of the reflection so they only have to photoshop the camera out of the mirror.
After you set up your tripod make sure the camera is propped up high enough to see the concavity of the sink and when you get to your flash shot, you'll probably have to turn the power of the flash down because half bats are much smaller than most of the other rooms in the house. Many of the same rules for half baths, like closing the toilet, propping the camera high enough to see the sink concavity, avoiding camera reflection in the mirror and using the fulcrum of the door to your advantage when applicable apply for full baths as well. Make sure again to focus primarily on sinks, counters and baths. In larger full baths, you may need to take multiple shots if the space is broken up or segmented. For example, if there is a nice jacuzzi that only shows partially in your primary bathroom shot, it is a good idea to take a more artful vignette shot at the jacuzzi as well since this kind of shot will stand out once it has been put through real estate image enhancement