FIFO i.e. First-in First-out is basically an accounting technique ordinarily used in day to day management of inventory and/or financial matters. This could, however, serve as a wonderful tool too for performing the duties and responsibilities by those who believe in the principles of equity, fairness and transparency in public life in managing their day to day affairs.
When we are managing important offices in administration, payment and accounting, health services, education, trade and industrial promotion, housing, vehicle licensing, public transport, welfare services, editing and publishing, and likewise other areas of public interest, it becomes more so important for us to follow this and use the element of discretion sparingly, more as an exception rather than as a rule (Unfortunately incidence of the use of discretion is rather high).
The simple rule of the game is that I will follow the order strictly by first attending to those who, or whose requirements, came in first and dispose of my day to day business in that order. It is an experience based conviction that this principle works ideally not only for the sake of equity, fairness and transparency but for efficiency, effectiveness and mass satisfaction as well. If you largely follow FIFO and use (merit based) discretion only occasionally, this will minimize the scope for dissent, dissatisfaction and resentment with your working besides enhancing your image and acceptability many fold, irrespective of the area you work.