This comes courtesy of Mindfulness in Plain English, one of the best books on meditation and mindfulness that I've ever come across.
The very process of observation changes what we observe.
For example, an electron is an extremely tiny item. It cannot be viewed without instrumentation, and that apparatus dictates what the observer will see. If you look at an electron in one particular way, it appears to be a particle, a hard little ball that bounces around in nice straight paths. When you view it another way, an electron appears to be a wave form, glowing and wiggling all over the place, with nothing solid about it at all. An electron is an event more than a thing, and the observer participates in that event by the very act of his or her observation. There is no way to avoid this interaction.
Meditation is no different. What you are looking at responds to you looking at it.
Thus, the process of meditation is extremely delicate, and the result depends absolutely on the state of mind of the meditator.
Here are the essential attitudes to success in the practice of meditation.
1) Don’t expect anything. Just sit back and see what happens. Treat the whole thing as an experiment. Take an active interest in the test itself, but don’t get distracted by your expectations about the results. For that matter, don’t be anxious for any result whatsoever. Let the meditation move along at its own speed and in its own direction. Let the meditation teach you. Meditative awareness seeks to see reality exactly as it is. Whether that corresponds to our expectations or not, it does require a temporary suspension of all of our preconceptions and ideas. We must store our images, opinions, and interpretations out of the way for the duration of the session. Otherwise we will stumble over them.
2) Don’t strain. Don’t force anything or make grand, exaggerated efforts. Meditation is not aggressive. There is no place or need for violent striving. Just let your effort be relaxed and steady.
3) Don’t rush. There is no hurry, so take your time. Settle yourself on a cushion and sit as though you have the whole day. Anything really valuable takes time to develop. Patience, patience, patience.
4) Don’t cling to anything, and don’t reject anything. Let come what comes, and accommodate yourself to that, whatever it is. If good mental images arise, that is fine. If bad mental images arise, that is fine, too. Look on all of it as equal, and make yourself comfortable with whatever happens. Don’t fight with what you experience, just observe it all mindfully.
5) Let go. Learn to flow with all the changes that come up. Loosen up and relax.
6) Accept everything that arises. Accept your feelings, even the ones you wish you did not have. Accept your experiences, even the ones you hate. Don’t condemn yourself for having human flaws and failings. Learn to see all the phenomena in the mind as being perfectly natural and understandable. Try to exercise a disinterested acceptance at all times with respect to everything you experience.
7) Be gentle with yourself. Be kind to yourself. You may not be perfect, but you are all you’ve got to work with. The process of becoming who you will be begins first with the total acceptance of who you are.
8) Investigate yourself. Question everything. Take nothing for granted. Don’t believe anything because it sounds wise and pious and some holy man said it. See for yourself. That does not mean that you should be cynical, impudent, or irreverent. It means you should be empirical. Subject all statements to the actual test of your own experience, and let the results be your guide to truth. Insight meditation evolves out of an inner longing to wake up to what is real and to gain liberating insight into the true structure of existence. The entire practice hinges upon this desire to be awake to the truth. Without it, the practice is superficial.
9) View all problems as challenges. Look upon negativities that arise as opportunities to learn and to grow. Don’t run from them, condemn yourself, or bury your burden in saintly silence. You have a problem? Great. More grist for the mill. Rejoice, dive in, and investigate.
10) Don’t ponder. You don’t need to figure everything out. Discursive thinking won’t free you from the trap. In meditation, the mind is purified naturally by mindfulness, by wordless bare attention. Habitual deliberation is not necessary to eliminate those things that are keeping you in bondage. All that is necessary is a clear, nonconceptual perception of what they are and how they work. That alone is sufficient to dissolve them. Concepts and reasoning just get in the way. Don’t think. See.
11) Don’t dwell upon contrasts. Differences do exist between people, but dwelling upon them is a dangerous process. Unless carefully handled, this leads directly to egotism. Ordinary human thinking is full of greed, jealousy, and pride. A man seeing another man on the street may immediately think, “He is better looking than I am.” The instant result is envy or shame. A girl seeing another girl may think, “I am prettier than she is.” The instant result is pride. This sort of comparison is a mental habit, and it leads directly to ill feeling of one sort or another: greed, envy, pride, jealousy, or hatred. It is an unskillful mental state, but we do it all the time. We compare our looks with others, our success, accomplishments, wealth, possessions, or IQ, and all of this leads to the same state— estrangement, barriers between people, and ill feeling.
The meditator’s job is to cancel this unskillful habit by examining it thoroughly, and then replacing it with another. Rather than noticing the differences between oneself and others, the meditator trains him- or herself to notice the similarities. She centers her attention on those factors that are universal to all life, things that will move her closer to others. Then her comparisons, if any, lead to feelings of kinship rather than of estrangement.
Explore your breath.
All living things exchange gases with their environment in some way or other. This is one of the reasons that breathing has been chosen as a focus of meditation. The meditator is advised to explore the process of his or her own breathing as a vehicle for realizing our inherent connectedness with the rest of life. This does not mean that we shut our eyes to all the differences around us. Differences do exist. It means simply that we de-emphasize contrasts and emphasize the universal factors that we have in common.
The recommended procedure is as follows: When we as meditators perceive any sensory object, we are not to dwell upon it in the ordinary egoistic way. We should rather examine the very process of perception itself. We should watch what that object does to our senses and our perception. We should watch the feelings that arise and the mental activities that follow. We should note the changes that occur in our own consciousness as a result. In watching all these phenomena, we must be aware of the universality of what we are seeing. The initial perception will spark pleasant, unpleasant, or neutral feelings. That is a universal phenomenon, occurring in the minds of others just as it does in our own, and we should see that clearly. By following these feelings various reactions may arise. We may feel greed, lust, or jealousy. We may feel fear, worry, restlessness, or boredom. These reactions are also universal. We should simply note them and then generalize. We should realize that these reactions are normal human responses, and can arise in anybody.
If you're interested in meditation, I highly recommend you pick up a copy of Mindfulness in Plain English.