Pastry is often the nemesis of the most experienced cook; it certainly has been one of mine.
One of the issues I used to have was making the raw pastry fit into the tin snugly. By pressing with your fingers, you often push right through the pastry and make unsightly holes or marks with your fingertips or nails. This is especially true if your pastry is very thin and if you are using fluted tart tins.
The trick is very simple. Simply roll a small ball of pastry and use this to gently ease the pastry into the edges of your tin. No holes, no fuss.