Shaking. You can either use a shaker or a frother hand mixer. Add the sugar first in the shaker or straight into the glass you are going to serve it on. Then add the coffee on top of the sugar. This is because coffee tends to stick at the bottom. Add approximately 20ml of water, enough to just slightly cover the ingredients. If you use a shaker, add the lid and shake till the froth gets thick. If you use the froth hand mixer, just mix it in the serving glass till it gets thick enough.
Add ice if you wish, and the milk (optional) and top up with cold water. Frappè is versatile. Some variations are: with a ball of ice cream inside the glass, with one tsp of coffee for a lighter touch, without milk if you prefer your coffee black, with aspartame or any other sugar replacement.