According to vedic numerology and astrology, the planet related to the psychic number should be befriended, and if the planet associated with the destiny number is not showing its full influence after you have passed the age of thirty-five, you should do the japa of that planet as well. In addition, you may do japa for any planet with which you wish to be in greater harmony.
It is said that in the Kali Yuga, the current age of dissolution, japa is the only method for realization of the divine within us. Japa, especially for the Sun, Moon and other planets, is a sure and time-tested method of creating calmness and hope and bringing peace and prosperity to your home.
Because the planets influence us largely through frequencies of sound and light (color), special mantras and yantras that are designed to work with a planet's energy are the best means of reaching a balance of energy that leads to a happy, healthy and inspired life. Remember that the planets are channels of energy and this energy gets converted into consciousness only when it finds an instrument that is properly capable of the task. This in a literal sense requires attuning to the planet's sound frequencies.
The seven planets preside over the first hour of the day (before sunrise) and meditation and chanting is most beneficial if done during this predawn hour. As each of the seven main planets (with the exception of rahu and ketu) is related to a day of the week, it is appropriate to chant the mantras of the planets following the days of the week :
This meditation can be followed by chanting to and meditating on other planets whose energies you feel you need to put in better balance, which might include Rahu (best on Sunday) and Ketu (best on Monday).
If you like to hear some mantras used in planet meditation, you can download the following mp3 files :
Sun Mantra - by Harish Johari - 12 seconds - 190 kB:
Moon Mantra - by Harish Johari - 10 seconds - 158 kB: