@Anna M. For photos you need to use a wide-angle lens and a tripod (You can see a tripod leg in the shadow on the bathroom photo). DSLR would be the best but you can even get good shots with a phone with a snap-on lens and a tripod. Results will vary by phone type though.
Also works well if you can remote fire the camera, that way you can get it into a corner and not have to stand behind it to shoot.
Open all drapes and turn on all lights (see the Kitchen Photos)
Also don't be afraid to experiment with cheap external battery powered lights that you can use to light up a dark area. A flashlight and a paper towel tube can do some wonderful things :)
Last tip would be to use an area or grid exposure setting and not a point (center point of lens) This way the camera will try and balance out the lighting on it's own across the whole area and not just the center of the lens.
Those should be some easy ways to improve your photos if you take them on your own.