While there are many different ways to temper chocolate (double boiler, immersion blender, etc), I prefer the ease of the microwave and the good ole seeding technique.
The general rules are to get the chocolate warm but not too hot, add about 1/4 of the original amount of chocolate (not melted) to the melted chocolate and stir to combine, bringing the combined chocolate to just above room temperature.
(1) Pour chocolate (8 oz here) into the glass measuring cup. Heat on high for 30 seconds. Even though the chocolate doesn’t appear to have changed much, stir the chocolate with a spatula.
(2) Heat on high for an additional 30 seconds. Stir.
(3) Heat on high for an additional 30 seconds. Stir. Your are looking for the chocolate to be warm to the touch (at least 100 degrees) and melted almost throughout.
(4) Add unmelted chocolate (2 oz here) and stir to melt, allowing the temperature of the chocolate to rise to a lukewarm (around 80 degrees). To test your temper, swirl a little chocolate along some wax paper. The chocolate should harden within 5 minutes.
(5) Use it! Tempered chocolate may be used and re-heated to a pouring consistency so long as it remains liquefied. Once the chocolate hardens, it will need to be re-tempered to be used.