Shukla Dashami is the name for the 10th Tithi (lunar day). It's the 10th Tithi of Shuklapaksha. It's nature is Saumya Prada, which can be interpreted as "soberness and clearness increase", "one that leads to placid state, state of happiness". It's good for following works: Upanayana, Alankar, Manglik works, peaceful and Paushtik works; marriage; installation; travel, conveyance; actions related to elephants, horses; enter; government works.
According to Muhurta Chintamani and Brihat Samhita Dharmaraja (Deity who's responsible for everything that's related to Dharma and righteous way of living) rules Shukla Dashami, thus it is auspicious for all acts of virtue, religious functions, spiritual practices and other pious activities. As for Poorva Kalamrita, Nāgas rule the 10th Tithi, thus Shukla Dashami also is auspicious period for gaining wisdom, secret knowledge. Nāgas also are related rebirth, administering medicine, the purging of poisons, and surgery, as well as waters (rivers, lakes, seas, and wells) and are generally regarded as guardians of treasure.
Being Poorna (that can be translated as "full", "complete" or "perfect") and ruled by Guru (Jupiter), 10th Tithi of Shuklapaksha is suitable for following works or actions: marriage, Upanayana, Manglik works, travel, tourism, coronation, peaceful & Paushtika actions.
During the vedic month Ashadha Shukla Dashami becomes Sompad (that can be translated as wealth, possession, success) Tithi, which is considered very auspicious in succeeding in works started during this Tithi. Also in Ashadha Shukla Dashami is Chakshush - Manvadi Tithi, which is considered to be extremely auspicious for any Punya Karma (Japa, Tapa, Dana, Havan, Homa etc.). But being Manvadi Tithi Shukla Dashami should be avoided in starting of education, Upanayana, marriage, ending of fasts, construction of house and entering thereof; travelling; plantation works.
During the vedic month Ashwina Shukla Dashami becomes Maasa Shoonya Tithi, which is considered inauspicious in succeeding in works started during this Tithi.
If Surya (Sun) transits through Simha (Leo) or Vrshchika (Scorpio) during Shukla Dashami, it becomes Dagdha Tithi (i.e. burned lunar day). 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.
NB! There're no Tithi Shoonya Lagnas or Nakshatras for Shukla Dashami that makes it extremely auspicious day for any activity (taking into consideration pre-cautions mentioned above).
