Holy Mother Church has been clear on the correct manner of praying for the dead and not to the dead, unless these dead are saints.
A little preposition makes a huge difference...
Here is a quotation from St. Augustine's Confessions to begin the conversation:
from "Book VI":
When, therefore, my mother had at one time— as was her custom in Africa— brought to the oratories built in the memory of the saints certain cakes, and bread, and wine, and was forbidden by the door-keeper, so soon as she learned that it was the bishop who had forbidden it, she so piously and obediently acceded to it, that I myself marvelled how readily she could bring herself to accuse her own custom, rather than question his prohibition. … because these, so to say, festivals in honour of the dead were very like the superstition of the Gentiles, she most willingly abstained from it. And in lieu of a basket filled with fruits of the earth, she had learned to bring to the oratories of the martyrs a heart full of more purified petitions, and to give all that she could to the poor; that so the communion of the Lord’s body might be rightly celebrated there, where, after the example of His passion, the martyrs had been sacrificed and crowned.
Some modern. secular customs do not follow older Catholic ones.
Waking, which is a European custom, is approved and frequently done in connection with Catholic funeral parlors.
Three days are usually set aside, although in some cultures, it is a week, to pray the rosary daily for the soul in purgatory. Sometimes, if a priest can make the evening rosaries, he might join the family and friends
A funeral Requiem Mass with the remains present is the time not for celebrating the person's life, or for eulogies, but for sincere prayers for the dead. Most people who were practicing Catholics would need such prayers to be released from the pains of purgatory.
Later, one can have Memorial Masses for the dead. In earlier years, these were sung and black vestments were used. I remember, as I sang in the choir for these types of liturgies for years.
One can have Masses said, and one can do plenary indulgences for the dead and the rules for obtaining those are at the bottom of this post.
One should visit the grave out of respect, but not over-indulging in grief. Our family would go once a year, using on Memorial Day, or November 2nd, weather permitting. Remember, purgatory is purgation for not dealing with even venial sins and imperfections, for not facing and being purged of one's predominant fault.
Remember, only the Church through apostolic succession can forgive sins in Confession, and only the Church through the Pope can grant plenary and partial indulgences for the dead (in this post, I am not referring to one's ability to gain an indulgence for one's self). Here is the Canon Law on this point. Only practicing Catholics, in other words, those in sanctifying grace, can gain indulgences as well. (I am not, also, referring to the great indulgence of Divine Mercy Sunday). Here, also, is a clarifying statement from St. John Paul II. http://www.vatican.va/holy_father/john_paul_ii/audiences/1999/documents/hf_jp-ii_aud_29091999_en.html
Canon Law--CHAPTER IV.
Can. 992 An indulgence is the remission before God of temporal punishment for sins whose guilt is already forgiven, which a properly disposed member of the Christian faithful gains under certain and defined conditions by the assistance of the Church which as minister of redemption dispenses and applies authoritatively the treasury of the satisfactions of Christ and the saints.
Can. 993 An indulgence is partial or plenary insofar as it partially or totally frees from the temporal punishment due to sins.
Can. 994 Any member of the faithful can gain partial or plenary indulgences for oneself or apply them to the dead by way of suffrage.
Can. 995 §1. In addition to the supreme authority of the Church, only those to whom this power is acknowledged in the law or granted by the Roman Pontiff can bestow indulgences.
§2. No authority below the Roman Pontiff can entrust the power of granting indulgences to others unless the Apostolic See has given this expressly to the person.
Can. 996 §1. To be capable of gaining indulgences, a person must be baptized, not excommunicated, and in the state of grace at least at the end of the prescribed works.
§2. To gain indulgences, however, a capable subject must have at least the general intention of acquiring them and must fulfill the enjoined works in the established time and the proper method, according to the tenor of the grant.
Can. 997 As regards the granting and use of indulgences, the other prescripts contained in the special laws of the Church must also be observed.
First, here is the CCC on indulgences in general:
1471 The doctrine and practice of indulgences in the Church are closely linked to the effects of the sacrament of Penance.
What is an indulgence?
"An indulgence is a remission before God of the temporal punishment due to sins whose guilt has already been forgiven, which the faithful Christian who is duly disposed gains under certain prescribed conditions through the action of the Church which, as the minister of redemption, dispenses and applies with authority the treasury of the satisfactions of Christ and the saints."81
"An indulgence is partial or plenary according as it removes either part or all of the temporal punishment due to sin."82 The faithful can gain indulgences for themselves or apply them to the dead.83
The punishments of sin
1472 To understand this doctrine and practice of the Church, it is necessary to understand that sin has a double consequence. Grave sin deprives us of communion with God and therefore makes us incapable of eternal life, the privation of which is called the "eternal punishment" of sin. On the other hand every sin, even venial, entails an unhealthy attachment to creatures, which must be purified either here on earth, or after death in the state called Purgatory. This purification frees one from what is called the "temporal punishment" of sin. These two punishments must not be conceived of as a kind of vengeance inflicted by God from without, but as following from the very nature of sin. A conversion which proceeds from a fervent charity can attain the complete purification of the sinner in such a way that no punishment would remain.84
1473 The forgiveness of sin and restoration of communion with God entail the remission of the eternal punishment of sin, but temporal punishment of sin remains. While patiently bearing sufferings and trials of all kinds and, when the day comes, serenely facing death, the Christian must strive to accept this temporal punishment of sin as a grace. He should strive by works of mercy and charity, as well as by prayer and the various practices of penance, to put off completely the "old man" and to put on the "new man."85
In the Communion of Saints
1474 The Christian who seeks to purify himself of his sin and to become holy with the help of God's grace is not alone. "The life of each of God's children is joined in Christ and through Christ in a wonderful way to the life of all the other Christian brethren in the supernatural unity of the Mystical Body of Christ, as in a single mystical person."86
1475 In the communion of saints, "a perennial link of charity exists between the faithful who have already reached their heavenly home, those who are expiating their sins in purgatory and those who are still pilgrims on earth. Between them there is, too, an abundant exchange of all good things."87 In this wonderful exchange, the holiness of one profits others, well beyond the harm that the sin of one could cause others. Thus recourse to the communion of saints lets the contrite sinner be more promptly and efficaciously purified of the punishments for sin.
1476 We also call these spiritual goods of the communion of saints the Church's treasury, which is "not the sum total of the material goods which have accumulated during the course of the centuries. On the contrary the 'treasury of the Church' is the infinite value, which can never be exhausted, which Christ's merits have before God. They were offered so that the whole of mankind could be set free from sin and attain communion with the Father. In Christ, the Redeemer himself, the satisfactions and merits of his Redemption exist and find their efficacy."88
1477 "This treasury includes as well the prayers and good works of the Blessed Virgin Mary. They are truly immense, unfathomable, and even pristine in their value before God. In the treasury, too, are the prayers and good works of all the saints, all those who have followed in the footsteps of Christ the Lord and by his grace have made their lives holy and carried out the mission the Father entrusted to them. In this way they attained their own salvation and at the same time cooperated in saving their brothers in the unity of the Mystical Body."89
Obtaining indulgence from God through the Church
1478 An indulgence is obtained through the Church who, by virtue of the power of binding and loosing granted her by Christ Jesus, intervenes in favor of individual Christians and opens for them the treasury of the merits of Christ and the saints to obtain from the Father of mercies the remission of the temporal punishments due for their sins. Thus the Church does not want simply to come to the aid of these Christians, but also to spur them to works of devotion, penance, and charity.90
1479 Since the faithful departed now being purified are also members of the same communion of saints, one way we can help them is to obtain indulgences for them, so that the temporal punishments due for their sins may be remitted.
1498 Through indulgences the faithful can obtain the remission of temporal punishment resulting from sin for themselves and also for the souls in Purgatory.
Rules current for obtaining a plenary indulgence for someone in purgatory (or one's self).
A plenary indulgence can be gained only once a day. In order to obtain it, the faithful Catholic must, in addition to being in the state of sanctifying grace:
—have the interior disposition of complete detachment from sin, even venial sin;
—have sacramentally confessed sins within three weeks (20 days);
—receive the Holy Eucharist on the same day as praying for the soul.
—pray for the intentions of the Supreme Pontiff.
One Our Father, one Hail Mary, and one Glory Be are sufficient, although many Catholics do three.