I personally love reading fantasy books like the Sword of Truth Series by Terry Goodkind because of the way he set's the scene, the way in which he describes his character's.
With a small amount of imagination one of those character's could be standing next to you in the room. I guess the point of an illustration essay is to make the words on the page come alive to the reader. Perhaps pretend you are describing your favourite show to someone who is blind, you don't want them to miss anything and you don't really want to give them too much info that overwhelm them. So you describe the crucial and best bits in detail.
Like opening that present - you don't need to open it all the way to see what it is... but you can look at the shape, shake it and maybe open one corner. I was told when describing something remember to use all your sense's, sight, touch, smell etc.
As for some examples - what do you like doing that you could share with other people?
Hope that helps
Mel
Mel Arnold