• Taking pictures on a cloudy day can be tricky. Always aim for a clear sky and make sure that there are no more than negligible amount of clouds on the sun, while taking images. Better if there is no cloud at all. Sometimes the upper atmosphere has a thin layer of clouds and if they are not going anywhere, then you don't have much of a chance to get a clear sky. Only in such cases take images when clouds(of upper atmosphere) are over it
• Taking Dark frames, flat frames, etc are not necessary in usual conditions but will be important if you do not regularly wipe your camera lens, or if there is dirt trapped inside the lens, or if your camera is old, or if your camera gets heated a lot.
• ISO 800 and Shutter Speed 1/800s seems to work best for taking images of sun in a clear sky, among all other combinations of ISO and Shutter speed. Also, this combination follows the rule that ISO should be reciprocal of the shutter speed for getting best exposed images.
• On a cloudy day, usually in winter time, the sun light is faint because of thin layer of clouds in the upper layer of the atmosphere, so it is better to use ISO 6400 and shutter speed around 1/250 s to 1/20s, depending upon how well-exposed images you are getting with the current faintness of the sun.
• Make sure that while clicking pictures, the screws on the tripod stands are tight, if they are not then you camera will move during photography and this will rotate the sun disc's image. This results in a nightmare for those who are going to stack it.
• Don't turn the lens while taking photos, the lens's focal length shouldn't change while you are taking photos, you cannot stack two sets of images, one of which was taken with focal length 200 and the other will focal length 300 mm.
• ALWAYS TAKE A SINGLE IMAGE FIRST AFTER FOCUSSING AND SEE IF YOU CAN SEE A FAINT SUN SPOT AND SHARP EDGES OF SUN, IF YOU CAN THEN YOU ARE READY TO CLICK IMAGES IN BURST.