I often practice freeing my mind of sensory experience related to the past and future. One way you can do this is to hold a conversation with yourself (and/or others) using a vocabulary that only describes your present experience. Aim to keep this heightened receptivity actively engaged in the process of observation of your present experience without judgement or interpretation. Notice the relationship between things and your response to them in the present and commit to extend these periods of learning, so that you develop a deeper understanding of attachment and the way it dictates your thoughts, feelings and beliefs.
This can be practiced almost anywhere, indeed should be, on the bus, in the train, or when walking, especially with others as it helps us see the similarities between us rather than the differences.
A higher level of learning can then be practiced by freeing the mind of sensory experience related to the present, but this can be challenging because the mind is usually unwilling to let go of what it believes to be true, despite overwhelming evidence to the contrary. I can manage the first stage, but the second is often beyond me.