Finely chop your chocolate (yes even if you are using chips) so that your chocolate melts easily. If you need to melt more than 8 ounces of chocolate at a time I suggest using my how to temper chocolate using the seeding method on my blog.
The process for melting is the same for all the chocolate except milk chocolate should not be heated higher than 86ºF (30ºC), milk chocolate no higher than 88ºF (31ºC), and semi-sweet and dark no higher than 90ºF (32ºC). I suggest melting and dipping one type of chocolate at a time.
Place the chopped chocolate into a heat proof bowl.
Heat the chocolate on full power in the microwave for 30 seconds and then stir to distribute the heat evenly throughout the chocolate.
Continue heating the chocolate in 10-15 second increments until the chocolate is about 90% melted and still below the maximum temperature for the type of chocolate you are using.
Continue to stir the chocolate until it's fully melted. If your chocolate begins to cool down 5 degrees and you still have un-melted pieces, you can continue heating in 5 second increments until they are melted but be very careful not to go over your max temp. If you do go over you can still temper your chocolate using the seeding method (see the link in my blog post)