Don’t Shake The Phone While Shooting- As mentioned above, an HDR image is composed by merging three different photos shot at very short time intervals (fraction of a second). So, it would great and optimum results only when you don’t move and camera for a few seconds after clicking the capture button. In case you shake the camera, you will get an image with halos and ghosting effect.
Take HDR Only When It Is Suitable- HDR photography lets you highlight the detail in the dark areas of the scene while not blowing out the details of the bright regions. So, it only makes sense to capture HDR images only when the subject has a dark foreground or a very bright background, or if you want to shoot a very bright object (say Sun) without compromising the details in the sky (say clouds).
Use Apps- Most of the phones have in-built support for HDR mode in their camera apps. The HDR mode in the stock camera apps does a decent job for taking images with high dynamic range, but in case you want to improve on that, or if your phone’s camera app doesn’t have an HDR mode, then you should go for third party camera or HDR apps on Google Play.