When you have done this you should develop the Four Protective Meditations for some minutes. These four are (1) recollection of the Buddhas attributes; (2) development of loving kindness or metta towards all living beings; (3) reflection upon the loathsome nature of our body; (4) reflection on the nature of death.
When you recollect the attributes of the Buddha you can select one of nine attributes. Out of these nine attributes of the Buddha you can choose the first or the second or any of the nine as the object of your meditation and reflect on it. Here Arahat is the first attribute. Arahat means the Buddha who is worthy of honour because he has completely destroyed all mental activities and attained to the cessation of all kinds of dukkha. You have to recollect this achievement of the Buddha, thinking about its meaning. Thats the worthiness of honour through his attainment of the cessation of all kinds of suffering by destroying all mental defilements so he lived in peace and bliss and happiness. When you recollect these attributes you feel happy and brave to face any kind of dukkha or suffering in the course of your meditation as well as in your daily life. This must be done about two minutes.
Then you have to develop your metta, loving kindness, the feeling of loving kindness towards all living beings, wishing all living beings peace and happiness, and free from all kinds of mental and physical suffering, dukkha. This feeling of detached love is developed in yourself. Then you feel happy and tranquil, your mind easily concentrated on any object of meditation. This must be done about five minutes.
After that you have to reflect upon the loathsome nature of the body, thinking about its repulsiveness such as blood, pus, phlegm, intestines, and so on. This body is full of these impurities and repulsiveness. The result is you are detached from this body to a certain extent because you find it loathsome or repulsive. This also must be done about two minutes.
Then after that you should reflect upon the nature of death. Life is uncertain, death is certain. Life is precarious and death is sure. Everyone who is born is subject to death. So all men are mortal. In this way you have to think about the surety of death for every living being. You can arouse strenuous effort in your practise by thinking, `Ill have to practise this meditation strenuously before I die, or before I am dead.
This is what the Buddhist meditational texts mention as a preliminary stage for both the Samatha meditator and Vipassana meditator. They are not compulsory, not indispensable. But the texts mention they should be done. These four protective meditations, recollection of the Buddhas attributes and development of loving kindness, metta, towards all living beings is the most important thing for a meditator to pacify his distracted mind and also to practise meditation happily and peacefully.