You can find a list of important dates for fasting in this calendar year. The list includes amavasya, pournami, sankatahara chatuthi which is the thei pirai chaturthi, and valar pirai chaturthi very auspicious for Lord Ganesha. Kaarthigai and sasti are days where we fast to get blessings of Lord Muruga. Fasting for Lord Vishnu is on thiruvonam and ekadesi days. Pradosham and Sivarathri is maintained to seek the blessing of Lord Shiva.