As Guru is auspicious by its nature and it rules Thursday, thus it is considered to be good day and all auspicious works can be done during it. The nature of it is "small, short" (in ancient Sanskrit - "Laghu" or "Kshipra"), thus all such types of works are good at this weekday. In combination with "small" Nakshatras (Nakshatras which are Hasta, Abhijit, Pushyami and Ashwini) activity related to this Nakshatras will be very fruitful. As for effectiveness - Thursday is effective during a day-time. Thursday is auspicious for everything related to yellow color, works, related to gaining wisdom, doing dharmic actions, related to tradition, God, etc. All works that somehow are related to something creative, divine and traditional are very auspicious at this day (as Brahma is a tutelary Devata of it). Adhi-Devata (superior deity who's ruling the day) of Thursday is Indra.
Works in following fields are prescribed for Thursday: Manglik (auspicious) works, Alankaar, Yagyas, Havan, Pitri Sharadh, worshipping, peaceful religious works, temple, installing of deity \ idol \ Moorti \ Prateema \ Yantra; education, gaining wisdom, knowledge related works, learning in general, working with Shaastras; truthful works related to understanding the sense of life, meditation; wearing new clothes and trading thereof, ornaments, starting living in the house, doctor, medicine, trading in medicine, health related works, fasting; physical works, development and expanding works; king; wealth, gold, silver; trees; elephant, horse, bullock; transport, travel.