Simple rule for simple syrup. Equal amounts of water are mixed with sugar until the sugar is melted. The problem with that basic recipe is that unless you keep a supply on hand you will have to wait for it to get cool.
So...I make mine a bit differently. I use one-half part water to 1 part sugar and put them into a pan on the stove on medium heat. Once the water boils and the sugar is dissolved, remove the pan from heat and pour the mixture into a heatproof vessel. Add one-half part ice cold water to this mixture. Voila...cool simple syrup! For example:
1/2 cup granulated sugar
1/4 cup water
Add together in saucepan and boil til sugar is dissolved
Remove from heat and pour the simple syrup into a heat proof container
Add 1/4 cup ice cold water and stir. Done and done!