Here's an extract from Abhishiktananda's book Prayer.
There certainly is no set method or technique, still less any short cut, whereby one can be brought into the inner sanctuary, to the summit of that "Horeb" which irresistibly draws anyone who has heard the Spirit's call (cp. 1 Kings 19.8). However, ... there is one practice whose effectiveness has been recognised for centuries in the spiritual traditions alike of India and of Eastern Christianity.
In India this is called namajapa, the prayer of the Name. Nama means name, and japa means prayer; the verbal root jap means "to murmer". It consists of the continual repetition of the name of the Lord in one or other of its traditional forms; either the name by itself, for example, Rama or Hari or Krishna; or else an invocation which contains the name, for example, Om namah Shivaya, "Glory to Shiva".
...As far as possible, the Name is given by a guru. The guru himself chooses a particular mantra (a formula of prayer or invocation) for the disciple, in accordance with the aptitude and needs of the one whom he is initiating into the prayer.
Among Christians the nearest equivalent to the Hindu namajapa is what is called in the Oriental Christian tradition "the Jesus Prayer". Here too the practice is either a simple repetition of the name of Jesus, or else the use of a longer invocation containing the sacred Name. In these days the most widely used invocation is "Lord Jesus, Son of the living God, have mercy on me, a sinner". The best introduction to this form of prayer is The Way of a Pilgrim (translated from the Russian by RM French.)
In this Christian prayer of the Name we are immediately struck by the stress on our sinful condition and our need for forgiveness. This constant prayer for forgiveness, which is equally characteristic of the whole liturgy of the Church, does not, however, in any way indicate a morbid concern with one's spiritual state, as is sometimes held. Rather it is one way of expressing a deeply personal experience of the love of God and the realisation that in forgiving us he reveals most fully his love and almighty power. In the last analysis, to pray forgiveness unites us with the deepest level of the divine mystery.
Hindu prayer is different. Sometimes, no doubt, the Hindu also prays for forgiveness and for divine help: pahi mam, raksha mam, tvam eva sharanam, "Have mercy, save me, you alone are my refuge". But most frequently he is content simply to praise and adore: Om namah Shivaya (Glory to Shiva), Om namah Narayanaya, (Glory to the "Son of Man"). Here too it would be improper to find in this almost exclusive stress on adoration the attitude of a proud Pharisee who feels no need to beg for divine forgiveness. At least in those who are truly spiritual, it is rather the sign of total self-forgetfulness and of lack of concern for all that affects them personally - in Christian terms, the complete trust of a child who knows that his father is caring for his needs and whose only personal wish is to continue gazing at him. Indeed, once God has been known in truth, how could anyone in the Presence of Most High give any thought to himself or his own affairs?