Pie charts provide a good visual representation of the data when the categories show some variation in size. When there are several similar-sized categories, a pie chart can end up looking cluttered and it may be difficult to interpret the data. In such cases consider whether a table would present the information more effectively.
It is usual for the different sectors of the pie chart to be arranged clockwise in order of magnitude. If there is a slice that does not contain a unique category of data but summarises several, for example "other types" or "other answers", then even if it is not the smallest category it is usual to display it last in order that it does not detract from the named categories of interest.
It is helpful to colour or shade the different slices so that they grade from dark to light tones as you move from the first to the last slice.