You can melt chocolate chips in a variety of ways -- but there are just as many things that can go wrong if you are not careful. For example, trying to melt chocolate chips in a pan over direct heat can result in burned chocolate even if you use very low heat. Using the microwave is another option, but you can easily overheat the chocolate if you are not careful and extremely attentive. Fortunately, you can melt chocolate chips for dipping fairly easily and consistently with the proper methods and precautions.
Examine any tools that will come into contact with your chocolate to make sure they are completely dry. These include the bowl of your double boiler and the spoon you will use to stir your chocolate. Even a drop of water on one of your tools can ruin the entire batch of melted chocolate by making it seize.
Pour the chocolate chips into the top of a double boiler. The double boiler should have water in its bottom section, but do not turn on the stove burner yet; you may not need to use it at all.
Heat any liquid that you wish to incorporate into your melted chocolate. Mixing in cream, for example, will make the chocolate runnier -- which you might prefer for dipping purposes. Pour this hot liquid over the chocolate chips in the double boiler. Stir the chocolate liquid mixture well with a spoon. Ideally, the heat from the liquid alone will be enough to completely melt the chocolate after several minutes of stirring. If this is not the case, or if you are not adding liquid to the chocolate, move on to the next step.
Turn the heat under the double boiler on to low. As soon as the chocolate chips begin to melt at all -- or immediately if you have already partially melted them with liquid -- begin stirring. Stir constantly until the chocolate chips are almost completely melted, then remove them from the heat. Stir for a few more seconds or longer to finish melting the chocolate chips.