Photospheres often suffer from image artifacts, empty spots, cut off objects or ugly transitions between the single shots. To improve your results, you should read the following lines.
It's recommended to take Photospheres while holding your smartphone in portrait orientation. Considering this, a full sphere is divided into 4 rows and consists of 41 photos. You start with the middle row which consists of 13 photos. The rows above and below consist of 10 photos whereas the top and bottom rows consist of only 4 photos per row.
There's no need to take all the 41 photos. However it's recommended to complete at least the middle 3 rows. Leaving out the top and bottom rows is not a big deal at all, but will result in black bars.
While taking the photos have a solid stand, hold your arms still and as close as possible to your body and slowly turn around your own axis. The smaller the radius the better will be the stitching of the single shots. When you're starting with a new row, never - really never - move your arms up or down. Just tilt your phone and keep turning around slowly.
The best way to do it: The lens of your phone's camera remains at the exact same spot while the phone is rotated around it when taking the photos. Or more simple, rotate your body around the camera and not the camera around your body. Keeping this in mind should help you to achieve best results even indoors.
Following these basics should allow you to easily create stunning Photospheres.
If you prefer to watch a video tutorial, we recommend this excellent one by Erica Griffin.