A prayer rule for one who is on the path of a God-pleasing life.
You ask about a prayer rule. Yes, it is good to have a prayer rule on account of our weakness so that on the one hand we do not give in to laziness, and on the other hand we restrain our enthusiasm to its proper measure. The greatest practitioners of prayer kept a prayer rule. They would always begin with established prayers, and if during the course of these a prayer started on its own, they would put aside the others and pray that prayer. If this is what the great practitioners of prayer did, all the more reason for us to do so. Without established prayers, we would not know how to pray at all. Without them, we would be left entirely without prayer.
However, one does not have to do many prayers. It is better to perform a small number of prayers properly than to hurry through a large number of prayers, because it is difficult to maintain the heat of prayerful zeal when they are performed to excess.
I would consider the morning and evening prayers as set out in the prayer books to be entirely sufficient for you. Just try each time to carry them out with full attention and corresponding feelings. To be more successful at this, spend a little of your free time at reading over all the prayers separately. Think them over and feel them, so that when you recite them at your prayer rule, you will know the holy thoughts and feelings that are contained in them. Prayer does not mean that we just recite prayers, but that we assimilate their content within ourselves, and pronounce them as if they came from our minds and hearts.
After you have considered and felt the prayers, work at memorizing them. Then you will not have to fumble about for your prayer book and light when it is time to pray; neither will you be distracted by anything you see while you are performing your prayers, but can more easily maintain thoughtful petition toward God. You will see for yourself what a great help this is. The fact that you will have your prayer book with you at all times and in all places is of great significance. Being thus prepared, when you stand at prayer be careful to keep your mind from drifting and your feeling from coldness and indifference, exerting yourself in every way to keep your attention and to spark warmth of feeling. After you have recited each prayer, make prostrations, as many as you like, accompanied by a prayer for any necessity that you feel, or by the usual short prayer. This will lengthen your prayer time a little, but its power will be increased. You should pray a little longer on your own especially at the end of your prayers, asking forgiveness for unintentional straying of the mind, and placing yourself in God's hands for the entire day.
You must also maintain prayerful attention toward God throughout the day. For this, as we have already mentioned more than once, there is remembrance of God; and for remembrance of God, there are short prayers.