You will want microwaveable containers to melt the chocolate in separately. Have parchment paper or a drying rack to let the cookies dry as well.
Take a cookie and only dip the front of the cookie (dipping the back gets it stuck to the parchment paper and the cooling rack breaking the cookie). Turn the cookie and ensure the entire top is covered in chocolate if you want.
Take your topping of choice and sprinkle it on top of the chocolate. Set your cookie down to cool and move on to the next one. Repeat until all your cookies are decorated.
You can place them in beautiful boxes to give as gifts or wrap in parchment paper with a bow. Serve them on a beautiful pie stand at your party.