Make pastry with butter and plain flour, using a whole egg to bind. This makes the pastry very easy to ahndle, so that it can be rolled out thinly.
Roll out thinly (about 3-4 mm). use a tumbler to cut some rounds and a shot glass or similar to cut smaller rounds. Use the larger rounds to line cake tin holes, fill with mincemeat and top with the smaller rounds. Brush with beaten egg and cook until golden. This method avoids an excess of pastry. You can sweeten the pastry with icing sugar but given that mincement is sweet I prefer not to.
As far as mincemeat is concerned, I usually use a jar as a starter, then add to it sultanas, raisins, chopped apples, peel etc., together with an extra handful of suet and sugar and spices to taste. I pour in some brandy/whisky/sherry/port and perhaps a bit of orange juice and leave to soak for a bit until sufficiently gloopy.
All a bit trial and error, and the exact composition depends, for instance, on the number of slightly tired apples which need using; but they seem to go down well