Spirituality is the individual approach to one's relationship with God. It involves making use of the tools of prayer and devotion which help you to live as a Christian the best way possible. Spirituality is, therefore, personal and many details of your spirituality will be largely dependent on your preferences.
Even so, there are some standard points that come in handy, especially if you are discerning whether you may be called to be a priest:
This depends on your circumstances, but a good guideline is to spend about an hour a day in prayer. This is best spent in the presence of God in the Blessed Sacrament, if possible. This time can include spiritual reading which helps to focus your heart and mind on God, a meditative rosary, praying the liturgy of the hours, or even just sitting in the Presence of our Lord. Be careful not to short shrift your prayer time, but also don't spend "too much" time. Time at prayer does not equal holiness, especially when you've got other concerns to attend to.
If a priest acts in persona Christi, then it makes sense that every priest - or man discerning the priesthood - should have a special relationship to the mother of Christ, who is also the Mother of the Church. The saints are models of the Christian life. The more we study and imitate their virtue, the closer our relationship with Our Lord will become. In addition, their lives are thoroughly inspiring. For inspiration in discerning a priestly vocation, consider reading about and praying to the following:
o St. John Vianney, patron saint of Priests
o St. John de Brebeuf and St. Isaac Jogues, martyrs of North America
o St. John Eudes, devoted to the Eucharist and the Sacred Heart
o St. John of the Cross, mystic o St. Francis Xavier, missionary to the Orient
o St. Maximilian Kolbe, devoted to Our Lady
o St. Josemaría Escrivá, Champion of the cause of virtue and holiness in daily life Of course, there are many others. Read more about priest saints.
One cannot seriously consider his vocation without frequent reception of Our Lord in Holy Communion. The Eucharist is the "source and summit of the Christian life," and it is especially important that a man discerning a possible vocation to the priesthood participate in the Eucharist frequently. While he should certainly never miss a Sunday Mass, daily Mass whenever possible is recommended.
Looking at the lives of the saints reveals that they frequent the confessional as a necessary part of their formation in holiness. One cannot be aligned to the will of God unless he is continually refining his motives and his heart to listen more clearly. There are a lot of moral dangers to contend with, after all! We need the grace offered by this sacrament to overcome these obstacles.
The sacrament of Penance should be used monthly, at least. Every week or every other week is likely to be more helpful. But be careful not to be scrupulous! It's important that one forgives himself - and forgets! Worrying over sins which one has confessed can be a way for the Devil to cause distraction or even despair!
The Sacred Heart of Jesus is the symbol of the union of God and Man - the whole reason for Jesus' mission, His Sacrifice on the Cross, and our participation in the Holy Sacrifice of the Mass. Devotion to the Sacred Heart is simply love for God Who became man to save all men. Within the Sacred Heart lies the complete mystery of salvation, which is the whole reason a man becomes a priest. Love of the Sacred Heart is an ideal devotion for a man discerning a priestly vocation.
Following these guidelines will open your heart to the Holy Spirit. They are not guarantees of a holy life. But keep opening your heart and mind to God, keep ascending closer to God, and do not let obstacles keep you from the most important decision of your life!