You can temper chocolate in your microwave or in a double-boiler. If you wish to use the double-boiler method, and you don't own a double-boiler, you can use a standard pot, and a metal bowl that can sit inside the pot without falling in. For larger batches, you'll probably have more luck with the double-boiler.
If you opt for the microwave, put chips or chopped chocolate into a microwave safe bowl, and gradually heat the chocolate in increments of about 30 seconds. Remove and stir at each interval. When most, but not all of the chocolate is melted, discontinue microwaving, and stir until all of the chocolate is uniformly melted.
If you choose to use your stove top, you do not want to melt the chocolate directly over the heat. You will scorch the chocolate, and ruin it. Instead, bring your pot of water to a boil, and place the inner pot or bowl over (but not touching) the boiling water. Reduce to a simmer and stir the chocolate as it melts. Beware of steam and condensation near the inner bowl (see "seizing" below).
For both methods: when the chocolate is melted, it needs to be at least 105 degrees F, (41 C). Remove from the heat, and add a block or several chunks of "seed" chocolate. Seed chocolate is room temperature chocolate that has been tempered properly.
Stir the chocolate until the seed chocolate is melted and the mixture falls to tempering range: 88-90 degrees F (31-32 C). The chocolate needs to remain in this range until it is used. Keep in mind, that different temperatures are required for the three different varieties of chocolate. For dark chocolate, the tempering range is 88-90 F (31-32 C), milk chocolate is 86-88 F (30-31 C), and white chocolate is 80-82 F (27-28 C).
If you follow these steps, your candies and coatings should set nicely, and the final product should be properly tempered (and could then be re-used as seed chocolate). If you make a mistake, remelt the chocolate and try again.
Other than scorching your chocolate, there is another pitfall, especially common if you are using a double boiler. Water. You don't want it near your melted chocolate! Though in liquid form, melted chocolate is extremely low in moisture, and you need to keep it that way. If you let a droplet of water fall into your melted chocolate, the cocoa and sugar will readily absorb it, creating a clump. Once the clumps (called "seizing") have formed, there's no way to reverse the process, and your batch of chocolate will no longer be usable for candy making. Hang onto it though, because it can be used in other recipes.
