Dear Mary,
Some excellent plenary indulgenced acts would be:
1) Making the Stations of the Cross in Church or where it it set up with blessed Crosses
2) Five decades of the Rosary before the AltarThe Blessed Sacrament or in an oratory or with a group.
3)Reading of sacred scripture for half an hour.
One needs to go to confession and partake of Holy Communion, together with prayer for the Holy Father (usually an Our Father, Hail Mary and Glory be)and then have the intention of gaining the indulgence for the Holy Souls. There are other indulgenced acts, but the above are the most popular and easiest to fulfill.
Alex