Keep in mind that in addition to the work to be performed, you should rouse in yourself a true sense of sorrow for and detachment from any sins. Be sure you will have made a good confession and received Communion within about 20 days.
Today, 31 December, you can gain a plenary indulgence by reciting the Te Deum. A plenary indulgence is gained for reciting the Te Deum on the last day of the year. On other days of the year, the indulgence is partial. You can recite it in Latin or the vernacular.
Tomorrow, 1 January, you can gain a plenary indulgence by reciting the prayer Veni, Creator Spiritus. On other days, the indulgence is partial.
I’ll make this easier still.
For the Te Deum, click HERE
For the Veni Creator click HERE
Indulgences! A spiritual work of mercy for others and good for your own soul too.