Buttercream Icing Recipe

I’ve never used a recipe for buttercream but one this has evolved over the last few years and I always get complimented on my icing.
Ingredients
1 stick of butter (softened)
1 block of cream cheese (softened)
about 1/2 cup Crisco or vegetable shortening
2lb bag of confectioners sugar
2 teaspoons flavor (optional)
about 1/4 cup water

Mix the butter, cream cheese and Crisco for about 2 minutes on medium speed until they are well mixed.  Add the flavor if you are using one.  If you want white icing, make sure your flavor is clear as a brown vanilla flavor for instance will make your icing slightly cream colored. 
Slowly add the sugar and once the icing stiffens (this is the hard part because I just do it by instinct) add more water a teaspoon at a time until all the sugar is gone and you have icing that is easily spreadable.  I make my icing much less stiff if I know that children will have to push it through a piping bag than if I have to pipe swirls on a cupcake.  If you use the whole 1/4 cup of water and the 2 teaspoons of flavor, your icing will be quite soft.  If it gets too soft you can just add more confectioners sugar and similarly if it’s too hard you can just add more water, but only a tiny bit at a time.