If you are new to the practice of mindfulness, the first thing you need to do is to be totally familiar with its definition, for hidden in plain sight in the definition is the clue to your successful practice.
Mindfulness, as defined by Jon Kabat Zinn, is paying attention purposefully, in the present moment, in a non-reactive way. The object of your attention or focus can be an external object, such as a flame on a candle, or an internal object. The three common internal objects are your body, emotions and thoughts.
For a beginner, it is easiest to start with the grossest object - one that is easy for you to focus on. In this respect, most beginners start their mindfulness training by learning to be fully aware of their bodily sensations, postures as well as noticing with greater details the daily experiences of the interactions between the five physical sense organs and the external objects.
For example, you can begin to become more mindful of your eating experience by remembering to be as fully aware as you can with the mechanics of chewing, tasting and swallowing each time you eat. You can also observe the movements of your limbs as you climb the stairs. Even while you are sitting and working at your computer, you can purposefully pay attention to your sitting posture, the pressure on your buttocks as well as the position of your spine and the various groups of muscles that are getting tense as a result of your posture.
Since paying attention to such mundane things that we have taken for granted is not something we do everyday at the conscious level, this is the first mental habit that we need to cultivate - to train our mind to focus on the objects of our conscious choice. This is by no means an easy first task as our everyday mind already has a well established habit of running all over the world with its attention, never staying with an object for any extended period of time. This everyday mind is what we called the monkey mind, for it behaves exactly like the restless monkey that jumps from one branch of a tree to another and never staying long in one place.
Next comes the next stage of learning to observe all our bodily experiences, and mental experiences, without being reactive to them. To achieve this, we need to train our mind to observe non-judgmentally so that the experience is not seen or filtered through our biased lenses. Again, this is a very different state of mind compared to our everyday mind that we are used to. Our everyday mind has the automatic tendency to prejudge things, people and events with our own likes and dislikes, which means we do not experience things as they really are. Instead, we experience them as we imagine them to be.
To be mindful, this non-judging quality is crucial as it is this quality of an open and curious mind that will give us a totally new perspective in our daily experiences. This is the beginner's mind that is open to all possibilities. When done right, mindfulness leads to a new state or quality of mind.
It is in this state of mind that you will begin to see things as they really are, free from your own filters, biases, prejudices, assumptions, beliefs and expectations.
Like all skills, it is the constant and continuous practice that will make you a better practitioner. Learn it now and habituated it in your life, and you will see your life transformed.