Use cream with NO LESS than 30% butterfat. The higher the butterfat content, the better stabilized it will be. Cream that is not ultra-pasturized will also hold its shape better.
Chill your mixing bowl (stainless steel and copper are best) and beaters in the freezer for 20 minutes. Your cream should also be cold.
If using instant pudding: Begin whipping the cream. When small bubbles appear, add instant pudding and sugar (if any). Continue to beat until stiff peaks form.
If using gelatin: Pour very cold water into a small bowl. Sprinkle gelatin on top of water to bloom. After 3 minutes add bloomed gelatin/water mixture to cold cream in the chilled mixing bowl. Begin to beat. When small bubbles appear, add flavoring of choice and sugar. Continue to beat until stiff peaks form.
DO NOT OVERBEAT! The cream will separate and turn to butter that you won't want to use as butter. ;)