Which form of meditation should I follow?
A good starting point is a very effective form of meditation taught by the Buddha, the ‘Mindfulness or Awareness of in-and-out Breathing’ (Anapanasati).
Here one's awareness is focussed and sustained at a point where the breath enters and leaves the body – tip of the nose or the the nostrils. The breath is an ideal object of meditation, being neutral (not arousing any attachments or emotions) and is conveniently available at all times.
The breath can be used as the object of meditation for both Samatha and Vippassana. In the practise of Samatha , the concentration is focused at a single point, namely the point at which the breath enters and leaves the body. With practise, the mind will gradually stop wandering and focus on the object of meditation.
In Vippassana (mindfulness), the meditator's attention is directed to the details of the breath. That is, when the breath enters or leaves the body, the meditator is aware that the breath is entering or leaving the body. The meditator is also aware if it is a short or a long breath etc. The important thing is, this is a process of pure obsevation in a detached manner.
Sitting down in meditation may be regarded as a training excersice. One should extend the practice of mindfulness to everyday life, eg being aware of thoughts that arise in the mind, bodily sensations and movements etc.
In Buddhist meditation, eradication of defilements of the mind (such as anger, hatred etc) and the path leading to release from the cycle of exsistance is vipassana. Samatha is a useful practice to calm the mind which will be helpful in developing mindfulness.
In the initial stage, regular practise for about twenty minutes a day is highly recommended, which can be extended as one progresses.