Wait for the temperature to rise, stirring occasionally to ensure the sugar dissolves
As the temperature gets close to boiling, begin stirring more often and don't walk away
Bring the mixture slowly to a boil over the low heat
Once the syrup hits a boil, turn off the heat
Allow the syrup mixture to cool to room temperature before storing
Just like making simple syrup, if you are using granulated sugar, you can measure it out by volume, and it is a simple 1:1 ratio. But if you are measuring the sugar by weight, when using brown sugar for instance, then use 75% sugar mass to water volume ratio. That is, use 300 mg of sugar to 400 ml of water.
Just like a regular simple syrup, this recipe is incredibly forgiving. A little over in one ingredient. A little under in another.