Should I grease my baking tins?

This helps stop food sticking. Brush the tin with melted butter or use some baking paper with a little butter on it to rub around the inside of the tin. 

Reheating Hollandaise or BĂ©arnaise sauce?

Never microwave! These are fragile emulsions and will split. Reheat by gently whisking over a double boiler on low heat. If the emulsion begins to split, try whisking in a spoonful of warm water, never add more butter.