Shukla Dwitiya is the name for the 2nd Tithi (lunar day). It's the 2nd Tithi of Shuklapaksha. It's nature is Mangala Prada, which can be interpreted as "one that augurs auspiciousness". It's good for following works: Upanayana, Deva Pratishta (installation of God's/deity's idol or picture), all Paushtik (developmental) and Manglik (the word "Mangala" can be translated from sanskrit as "auspicious") works, Alankara (ornamentation),
ornament making and wearing, starting and ending fasts, activity
related to house, government related activity, treasury, army,
travelling, music, art, sculpture, marriage.
Brahma (a God of creation, first deity of Hindu Triad - Brahma, Vishnu and Shiva) is Devata which rules Dwitiya (according to Muhurta Chintamani and Poorva Kalamrita). Thus, all works that are related to creation or any kind of auspicious undertaking are suitable for this day. As for Brihat Samhita, Shukla Dwitiya is ruled by Vidhata (as per Brahma-Purana - one of Ādityas, son of Daksha and Aditi) or Shrashta (one sacred form of Surya, the Sun).
Being Bhadra (that can be translated as "lucky") and ruled by Buddha (Mercury), the 2nd Tithi of Shuklapaksha is suitable for following works or actions: marriage, Upanayana, ornament making and using, clothes; art; travelling by elephant or horses, travel, conveyance; making of roads; oil massage.
During the vedic month Jyaishta Shukla Dwitiya becomes Sompad (that can be translated as wealth, possession, success) Tithi, which is considered very auspicious in succeeding in works started during this Tithi.
During the vedic months Shravana and Bhadrapada Shukla Dwitiya becomes Maasa Shunya Tithi. Anuradha Nakshatra also becomes Tithi Shoonya if it falls on Shukla Dwitiya. It's considered that all auspicious works done during Tithi Shoonya periods will be destroyed.
If Surya (Sun) transits through Dhanu (Sagittarius) or Meena (Pisces) during Shukla Dwitiya, it becomes Dagdha Tithi. Dagdha Tithis are known as inauspicious for starting any kind of work. Rishi (sage) Brihaspati also says that if Dagdha is present either for Lagna or Tithi then it inflicts death.
