Alright: here's the deal with chocolate. Chocolate is fairly finicky... it overcooks easily, but also cools and changes consistency equally as easily. Pretty much the best method to deal with chocolate is to use a double boiler. Sounds complicated? It isn't.
You don't really need special equipment, just 2 pots, 1 that fits inside the other. The smaller pot will hold the chocolate, the larger one will hold the water. In french, they call this method the "bain-marie" or "water bath." I like that.
So all you have to do is simmer/boil the water, place the smaller pot with chocolate in its bath (the larger pot) and stir constantly until the chocolate is melted. Note: because chocolate can overcook and become grainy, you want to take it off the heat as soon as it has your desired consistency.
Sam: I think you'll find it much more easy to drizzle chocolate when prepared like this! You can also try playing around with adding ingredients to the chocolate that will change the way it cools and tastes. Chocolate sauces (vs. chocolate for dipping) usually have cream or butter added, as well as sugar and some liqueur for flavoring.