Visualise does not mean you should try to paint a picture.

Concentrate instead on evoking complete confidence that Guru Rinpoche or Vajradhara is present before you, vivid and vibrantly alive, surrounded by all the buddhas and bodhisattvas.

I must stress here that visualise does not mean you should try to paint a picture of the refuge tree in your mind; that would be impossible. Visualisation is very like thinking about the person who is closest to you in this life—your mother, for example.

Try imagining her standing in front of you right now. As you do so, I’m quite sure you are not thinking about the exact shape of her ear. Or whether or not her toes curl. Or how many moles she has on her back. In fact, that kind of detail has probably never even occurred to you. At the same time, I am equally sure that you have created a strong sense of your mother in your mind and that you are completely confident it really is her.

This is how you should visualise the objects of refuge, and the confidence you feel in your visualisation is of utmost importance.

~ Dzongsar Khyentse Rinpoche