Appamāda - What is it? How to practise it? Benefits?
Pamada is a condition of a happily misbehaving child or a drunken person enjoying oneself too much. A type of silly joyful carelessness that assumes no concern or responsibility for results of one's actions. There are many translations of this word - laxity, sloppiness, but the one I find particularly insightful is "indulging".

Appamada then is a sober, grownup, calculated attitude to things. A grownup may relax a little, but never loses sight of what results will the actions bring. Hence the usual translation, heedfulness, or my preferrence -  "sobriety". 

One metaphor Buddhism uses a lot is that of intoxication. The three basic intoxicants of desire/obsession, negativity, and confusion/delusion cause the state of pamada, when one acts without proper regard for the consequences.

The practice of Appamada is certainly related to mindfulness, remaining aware and remembering the teaching at all times, but here the emphasis is on karma, or action and its expected result. Not only the physical action of course, but mental activity as well, including upadana, or fueling certain thoughts by giving them attention. We can either indulge in harmful thoughts uncontrollably, further fueling our intoxication, or be deliberate about our thinking, which leads to cessation of suffering. This last application of appamada can't be emphasized enough. 

Appamada means always staying in planned, deliberate, results-oriented frame of reference, as opposed to merely acting out one's emotions and impulses. Every time before we think or say or do something, we ask ourselves, what will this achieve?

So that's one aspect, always being deliberate, and the other aspect is not letting oneself get intoxicated. We get intoxicated every time we get aroused by the scent of an external source of joy, or by a particularly inspiring form of negativity. We get excited off balance by the thought of either reward or righteous anger. If we let ourselves get emotionally intoxicated all the time, we practically never spend time being emotionally sober, which makes us mentally weak. Instead, staying sober and collected requires a certain kind of strength and will power. In a way, you always keep your spine straight, your feet on the ground, your eyes open, your mouth shut. That's appamada, sobriety.