When making small individual tarts it is best to roll your pastry into a log (rather than a disc) before chilling and resting.

When you come to rolling out the pastry, cut the log into slices and then roll out each portion into a round before pressing into the tins. This no-fuss method means there is very little pastry offcuts and no need to re-roll scraps (which often causes the pastry to shrink when baking), ultimately giving you more even tart shell cases. 

When making a pie or tart there is no need to grease the tin before you line it with pastry – the high butter content in the pastry will naturally stop it from sticking to the tin.

If you grease your tin, the pastry is more likely to slip down the sides/shrink during baking leaving you with a tart case that with very short sides and not much room for your filling.