Occasionally projects just take off unexpectedly, sometimes you can work away at sketches and ideas for years before they are published. There are a number of authors I would be eager to illustrate. ↗
More often than not, however, the person who flatly states 'Elves aren't like that!' is hard pressed to describe how they really look.... as if Tolkien has summoned archetypes from so deep in our minds that we can only recall them incompletely. ↗