1 night of letting fruits and liquor soak in the sangria
In order for the sangria to absorb more fruitiness and for the fruits to absorb more wine and liquor, the best way (but more cumbersome) is to mix the fruits and the liquors of your liking the night before in jugs and seal each jug with a cellophane wrapping (sangria is still made of wine, so we have to care for the minimum contact with air on a long period of time). Then keep all the jugs in the fridge until service. But for that you need a lot of storage place in your fridge in order to have enough every time for 1 night of sales of sangria.
Temperature and Ice: The sangria must be as cold as possible before adding any ice cubes in it for the service as you want the sangria to be diluted as little and slowly as possible. This is why it is best to keep the sangria in the fridge until the service. This dilution also depends of course on the “room temperature” which could be out door. The best is to try by yourself to set the amount of ice you have to add.
The Perfect Glass: Since sangria has sometimes a lot of ingredients which are not consumed and have to be filtered by the mouth, it is much better to have a glass shaped as a whiskey glass (large and low) than a high glass. Also, we should never use a glass which has a stem (except if you want the customer to confuse sangria with wine!).