The visualisation, reflections and the repetition of loving-kindness are devices to help you arouse positive feelings. You can use all of them or one that works best for you. When the positive feelings arise switch from the devices to the feelings, as it is the feelings that are the primary focus. Keep the mind fixed on the feeling, if it strays bring it back to the device or if the feeling weakens or is lost then return to the device, for example, use the visualisation to bring back or strengthen the feeling.
The second stage is 'Directional Pervasion' where you systematically project the aroused feeling of loving-kindness to all points of the compass: north, south, east and west, up and down, and all around. This directional pervasion can be enhanced by bringing to mind friends and communities in the cities, towns and countries around the world.
Non-specific pervasion follows, which tends to spontaneously happen as the practice matures and is not discriminating. There is no specific object but just naturally radiating feelings of universal love. The practice has then come to maturity in that it has changed particular love, preferential love, which is an attached love to an all-embracing, unconditional love!
Loving-kindness is a heart meditation and should not be seen as just a formal sitting practice removed from everyday life. So take your good vibes outside into the streets, at home, at work, into your relationships. Applying the practice to daily life is a matter of directing a friendly attitude toward everybody you come into contact with.
May you be happy hearted!