I recently created an illustration of Charlotte Tilbury's new Eyes to Mesmerise cream eyeshadow.
I thought I would share my process with you, in particular how I created the illustration above. As I was working I took screenshots which I have turned into the following GIF.
I usually start with a very rough sketch to get the proportions correct and over that I create a more detailed outline to work from. Using the outline I add blocks of colour, I then remove the outline after it is completely filled in. I then begin building up the image by adding shadows, followed by highlights. Finally I add any textures and outlines required.