Prepare a baking sheet by lining it with aluminum foil. or wax paper.
Combine the chocolate chips or chopped chocolate and the shortening in a large microwave-safe bowl, and microwave until the chocolate is melted, stirring after every 20-30 seconds. When chocolate gets overheated it thickens and becomes unworkable, so watch your chocolate carefully! Take it out of the microwave when there are still unmelted chips remaining, and stir until the final chips melt.
If dipping pretzel rods, hold a rod by one end and dip it in the chocolate, leaving an inch or two uncovered. If you are dipping pretzel twists, drop the whole pretzel in the chocolate and submerge it slightly. Use a fork to pull the pretzel out of the chocolate. Shake the chocolate-dipped pretzels several times to remove excess chocolate, and place it on the prepared baking sheet. If you are using sprinkles or small candies, sprinkle them on when the chocolate is still wet. Repeat with remaining chocolate and pretzels.
Place the pretzels in the refrigerator for about 30 minutes to set the chocolate.
If desired, melt the white chocolate and drizzle it over the pretzels for a decorative look. Briefly return the candy to the refrigerator to set the white chocolate before serving.