To make a perfect easy caramel every-time, simply add one or two drops of vinegar and just enough water to wet the sugar. The idea is to lower the PH. you can also use a small pinch of citric acid or cream of tartar if you have. lemon juice won't work as it will turn bitter as the sugar cooks. Alternatively, an invert sugar such as corn syrup or golden syrup will work beautifully.