The process of our spirit disconnecting from the physical body [upon death] is accompanied by the dissolution of all gross and subtle thought-states or mental patterns. At this point there is nothing covering the basic state of mind at all. If we haven’t trained, then the basic state won’t last longer than a single glimpse. But if we have trained, then at that moment complete enlightenment is very likely.
The reason why training in this lifetime can yield such great benefit after death is because in the bardo state our mind is not connected to a body, so it is free of the continual obscuration we experience in our life-time. Right now we might recognize our own mind in a brief glimpse, only to have it immediately covered up again. But after death, the obscurations created by the body are not there. Only through practice can you overcome this cognitive obscuration. Through training, you will eventually reach the irreversible state of non-regression, no falling back. This is the real, true outcome, the profit earned through all the effort of practice.
Basically there is nothing to do at all in this practice besides training in being stable.
—Tulku Urgyen Rinpoche