As an exception to most baking, make sure to use ingredients as cold as possible when making pastry: so cubed butter straight from the fridge and ice cold water. Keeping pastry cold helps avoid overworking the gluten and keep it relaxed to avoid shrinkage during baking.
Handle the pastry dough as little as possible throughout making. This is especially important when bringing it together, as overworking the gluten will lead to tough pastry.
When placing the pastry into the tin, try not to stretch the dough to make it fit. Stretching the dough may look fine once in the tin, but doing so will result in the dough shrinking back to its pre-stretched size and shape during baking, spoiling the look of the tart.
Chill the pastry again once rolled and shaped into the tin. Chilling the pastry a second time allows the gluten to relax again, helping it hold its shape better and not be tough once baked.
During cooking of the creme pat, make sure to keep stirring it throughout the cooking time or you will end up with a lumpy end result.
Once the custard has finished cooking, transfer it to a clean bowl immediately and cover with cling film touching the surface. This stops a skin forming on top of the crème pâtissière as it cools, keeping it lump free ready to be used in the strawberry tart.
Place the halved strawberries on a piece of kitchen towel to absorb some of the moisture before placing on the tart.