Please click here to read all about the importance of the quenelle. And I'm not kidding--the quenelle is a shape you must learn to make if you want to plate an elegant dessert.
The term "garnish" is a very broad one. A garnish is anything on the plate that is not the main item. A banana split is a banana garnished with ice cream, sauces, whipped cream, nuts and a cherry.
Look at this beautiful dessert. The main component appears to be 
some sort of chocolate cake. The garnishesare the chocolate glaze, cut strawberry, grapes, that pale sauce and what is possibly strawberry-grape sorbet.
Broaden your mind a bit and expand your definition of "garnish" past a wee sprig of mint or a dusting of powdered sugar. Sure, those are garnishes, but don't limit yourself by a narrow definition.
I've divided garnishes into four main textures or mouthfeels--Creamy, Crunchy, Crispy and Other, thusly:
Aside from these four categories, there are also many ways to garnish a plate without cooking or baking anything:
- Put cocoa powder or powdered sugar in a sifter and then sift over half the plate.
- Cut a template out of a cake box or other thin cardboard, place it on your plate or on top of your dessert before dusting with powdered sugar or cocoa powder. Carefully remove the stencil, and you'll have a beautiful design on your dessert.
- Sprinkle some finely chopped nuts or crushed cookies on the plate.
- Decorate the plate with powdered spices. Use some restraint here.
- Highlight a sweet dessert with a few flakes of fleur de sel or other finishing salt.
- Garnish with a small dice or matchsticks of fruit.
- Garnish with herbs or edible flowers.
