About plenary indulgences, this is the easiest way I know of receiving one:
34. PRAYER, "EN EGO," ETC., BEFORE A CRUCIFIX.
Pope Pius VII., by a decree of the S. Congr. of Indulgences, dated
April 10, 1821, granted -
A plenary indulgence to all who shall devoutly say the following
prayer before any representation of Jesus crucified, with contrite
hearts, praying for the wants of Holy Church, after Confession and
Communion.
En ego, O bone et dulcissime Jesu, ante conspectum tuum genibus me
provolvo ac maximo animi ardore te oro atque obtestor ut meum in cor
vividos fidei, spei, et charitatis sensus, atque veram peccatorum
meorum poenitentiam, eaque emendandi firmissimam voluntatem velis
imprimere: dum magno animi affectu et dolore, tua quinque Vulnera
mecuм ipse considero, ac mente contemplor, illud prae oculis habens,
quod jam in ore ponebat suo David Propheta de Te, O bone Jesu:
"Foderunt manus Meas et pedes Meos; dinumeraverunt omnia ossa Mea."
O good and sweetest Jesus, before Thy face I humbly kneel, and with
all fervour of soul I pray and beseech Thee to vouchsafe to fix deep
in my heart lively sentiments of faith, hope, and charity, true
contrition for my sins, and a most firm purpose of amendment; whilst I
contemplate with great sorrow and love Thy five Wounds, and ponder
them over in my mind, having before my eyes the words which, long ago,
David the prophet spoke in his own person concerning Thee, my Jesus:
"Foderunt manus Meas et pedes Meos; dinumeraverunt omnia ossa Mea," -
They digged My hands and My feet; they numbered all My bones." Ps.
xxi. 17,18.
Source:
http://www.liturgialatina.org/raccolta/contents.htm