According to the original protocol of Hira Ratan Manek, there is no need for preparation for Sungazing, but many have found that it can be beneficial, especially if you practice over longer periods. For the practice of Sunmeditation, I have explained about a dozen preparatory meditations that you can also use for Sungazing. Just try them :). The video is in English, with some german subtitles.

Some Sungazers also have experienced the following preparations as helpful:
– Alternating breathing
– Fire breathing
You should find more information regarding these in the internet.

Nevertheless, it should be clearly said that it does not require any aids to practice Sungazing. Sungazing is a method that works through devotion. Be very aware if you add willpowered techniques such as pranayama (eg, through fire breathing). This can also backfire completely, because these are two completely different ways. The Ego can (but does not have to) very easily intervene via the control of the will, which is impossible with devotion. As long as you are still fundamentally ego-controlled – and this is the case with all who do not yet completely embody the true Self – special caution applies. The meditations presented in the video use the influence of willpower as little as possible, but go as far as possible through devotion.